THE  LIBRARY 

OF 

THE  UNIVERSITY 
OF  CALIFORNIA 

PRESENTED  BY 

PROF.  CHARLES  A.  KOFOID  AND 
MRS.  PRUDENCE  W.  KOFOID 


tn. 


PLATE  1 


, 
••' 


/ 


White  Cells  of  the  Blood,  Leukocytes,  Acting  as 
Phagocytes  or  Cell  Eaters;  Streptococci  in  Chains 
Being  Consumed. 


ELEMENTARY 

BACTERIOLOGY 


AND 


PROTOZOOLOGY 

THE  MICROBIOLOGICAL  CAUSES  OF 
THE  INFECTIOUS  DISEASES 


BY 


HERBERT  FOX,  M.D. 


DIRECTOR     OF    THE     WILLIAM    PEPPER     LABORATORY      OF      CLINICAL     MEDICINE      IN     THE 

UNIVERSITY   OF   PENNSYLVANIA;     PATHOLOGIST  TO   THE   ZOOLOGICAL 

SOCIETY  OF   PHILADELPHIA,    ETC. 


ILLUSTRATED    WITH    67    ENGRAVINGS    AND 
5  COLORED  PLATES 


LEA  &  FEBIGER 

PHILADELPHIA    AND    NEW    YORK 
1912 


Entered  according  to  the  Act  of  Congress,  in  the  year  1912,  by 

LEA   &   FEBIGER, 
in  the  Office  of  the  Librarian  of  Congress.      All  rights  reserved. 


sU 

PREFACE 


THE  present  work  has  been  prepared  to  give  the 
nurse  and  the  beginner  an  idea  as  to  the  nature  of 
microorganisms  and  their  relation  to  the  world's 
economy,  especially  in  disease.  For  this  reason  much 
technical  material  has  been  omitted,  especially  in  the 
subject  of  biological  differentiation.  Emphasis  has 
been  laid  upon  how  bacteria  pass  from  individual  to 
individual,  how  they  enter  the  body  and  act  when 
once  within,  and  their  manner  of  exit.  Such  general 
information  concerning  the  character  of  the  disease 
process  has  been  included  as  seemed  necessary  to 
clarify  the  nature  of  the  microbe  action.  Indeed,  the 
subject  matter  in  many  places  is  but  elementary 
bacteriological  pathology.  During  the  preparation  of 
the  work  the  author  has  had  in  mind  a  question  he 
has  been  asked  repeatedly:  How  do  bacteria  produce 
disease?  That  this  question  is  answered  as  simply 
and  as*  well  as  our  knowledge  of  today  permits  is 
the  author's  sincerest  hope. 

H.  F. 

PHILADELPHIA,  1912. 


M3584Q8 


CONTENTS 


CHAPTER  I 

INTRODUCTION — HISTORY — THE  PLACE  OF  MICROORGAN- 
ISMS IN  NATURE 17 

CHAPTER  II 

GENERAL  MORPHOLOGY — REPRODUCTION — CHEMICAL  AND 

PHYSICAL  PROPERTIES 22 

CHAPTER   III 

GENERAL  BIOLOGY,  INCLUDING  THE  CHEMICAL  CHANGES 

WROUGHT  BY  BACTERIA 33 

CHAPTER   IV 

METHODS  OF  STUDYING  MICROORGANISMS — STERILIZATION 

BY  HEAT 37 

CHAPTER  V 

DESTRUCTION  OF  BACTERIA  BY  CHEMICALS,  AND   THEIR 

PRACTICAL  USE 48 

CHAPTER   VI 
THE  RELATION  OF  BACTERIA  TO  DISEASE — IMMUNITY     .       58 

CHAPTER   VII 

PREPARATIONS  FOR  AND  PROCURING  OF  SPECIMENS   FOR 

BACTERIOLOGICAL  EXAMINATION  71 


vi  CONTENTS 


CHAPTER  VIII 

THE   ACUTE    CHIEFLY    LOCALIZED    INFECTIONS    OF    Pus 

NATURE — THE  PATHOGENIC  Cocci  77 


CHAPTER   IX 

THE  ACUTE  SELF-LIMITED  INFECTIONS 98 

CHAPTER  X 
THE  MORE  CHRONIC  INFECTIOUS  DISEASES     ....     138 

CHAPTER  XI 

VARIOUS  PATHOGENIC  BACTERIA  NOT  ASSOCIATED  WITH 

A  SPECIFIC  CLINICAL  DISEASE 164 

CHAPTER  XII 

YEASTS  AND  MOULDS 180 

CHAPTER   XIII 

BACTERIA  IN  AIR,  SOIL,  WATER,  AND  MILK    ....     189 

CHAPTER  XIV 
DISEASES  DUE  TO  PROTOZOA 200 

CHAPTER  »XV 

DISEASES  OF  UNKNOWN  ETIOLOGY    .  215 


GLOSSARY  221 


BACTERIOLOGY  AND  PROTOZOOLOGY 


CHAPTER   I 

INTRODUCTION— HISTORY— THE  PLACE  OF 
MICROORGANISMS  IN  NATURE 

INTRODUCTION 

THE  study  of  disease  has  brought  to  light  many 
facts  which  demonstrate  the  effect  of  the  association 
of  different  forms  of  life.  Chief  among  these  is  the 
fact  that  minute  beings  live  upon  greater  ones,  either 
harmlessly  or  to  the  detriment  of  the  latter.  The  study 
of  these  small  creatures  is  called  microbiology,  this 
being  the  portion  of  general  biology  in  which  the  use 
of  magnification  is  necessary.  Bacteria  are  classified 
as  plants  and  their  study  is  called  bacteriology.  The 
smallest  animals,  protozoa,  are  considered  in  the  sub- 
ject of  protozoology.  To  explain  the  causation  of 
infectious  diseases  the  physician  has  been  obliged  to 
study  both  of  these  subjects,  that  is,  the  large  field  of 
microbiology.  The  lowest  forms  of  life  are  unicellular 
bodies  capable  of  leading  an  independent  existence,  in 
contrast  to  the  single  units  of  the  cell  groups  which  go 
to  make  up  the  compound  organism,  a  higher  animal 
or  a  plant.  Some  of  these  single-celled  bodies  have 
2 


18  HISTORY 

characteristics  placing  them  without  question  among 
the  plants,  while  others  with  equal  definiteness  belong 
to  the  animals.  The  line  between  is  by  no  means 
sharp,  and  much  difference  of  opinion  exists  among 
investigators  as  to  the  borderline  forms. 

HISTORY 

The  existence  of  more  or  less  independent  forms  of 
life  invisible  to  the  naked  eye  was  first  proven  about 
two  and  one-half  centuries  ago  by  Van  Leeuwenhoek 
and  Kircher,  who  actually  saw  and  described  what 
were  called  animalculse.  The  first  conception  of  the 
existence  of  such  microscopic  forms  cannot  be  accred- 
ited to  these  observers,  since  so  long  ago  as  in  the 
fourth  century  B.C.  Aristotle  suggested  the  possibility. 

As  might  be  expected,  these  single-celled  bodies  were 
not  seen  until  the  development  of  lens-making  per- 
mitted accurate  enlargement.  The  greatest  advances 
have  been  made,  furthermore,  since  the  perfection 
of  the  compound  microscope  in  the  early  years  of 
the  nineteenth  century.  It  is  also  noteworthy  that 
those  who  might  be  considered  the  founders  of  this 
science,  so  important  to  physicians,  were  botanists 
and  chemists.  The  most  important  consideration  for 
the  early  observers  was  the  relation  that  these  minute 
bodies  bore  to  the  spoiling  of  food  and  water.  Indeed, 
most  physicians  of  the  past  and  not  a  few  of  the  present 
have  discredited  the  relation  of  bacteria  to  disease. 
The  first  opinion  upon  the  relation  of  specific  disease- 
producing  bacteria  came  in  the  middle  of  the  eighteenth 
century,  but  such  a  theory  could  not  be  proven  until 


HISTORY  19 

about  thirty  years  ago,  when  Koch  made  it  possible 
to  separate  the  various  individual  bacterial  species 
and  enabled  us  by  a  series  of  postulates,  to  study  the 
relation  of  the  germs  to  their  particular  disease.  The 
great  proof  of  the  existence  of  bacteria  came  from 
the  man  who  may  be  considered  the  founder  of  the 
modern  science  of  bacteriology,  Louis  Pasteur,  a 
French  chemist,  who  demonstrated  beyond  question 
that  bacteria  produce  fermentation,  and  that  fer- 
mentable materials,  if  protected  from  the  air,  remain 
without  bacteria.  There  succeeded  to  this  proof 
others  to  the  effect  that  bacteria  are  ubiquitous, 
and  that  they  are  carried  in  the  dust  or  probably 
alone  by  air  currents.  His  experiments  also  showed 
that  spontaneous  generation  (the  arising  of  living 
forms  anew  from  the  elements  of  nature,  and  not 
from  preexisting  living  forms)  of  bacteria  does  not 
occur.  The  results  of  Pasteur's  work  received  prac- 
tical application  also  at  the  hands  of  Koch  and  Lister. 
The  former  devised  methods  for  the  cultivation  and 
study  of  the  individual  species  and  followed  this  up 
by  discovering  the  organisms  causing  tuberculosis, 
anthrax,  and  cholera.  Lister,  shocked  by  the  appalling 
mortality  in  the  hospitals  from  gangrene  and  septic 
poisoning,  established  methods  by  which  bacteria 
from  the  air  and  from  infected  cases  were  excluded 
from  healthy  surgical  cases.  To  him  the  basic  prin- 
ciples of  modern  antiseptic  and  aseptic  surgery  are  due. 
Throughout  all  the  history  of  microbiological  devel- 
opment it  has  been  possible  to  progress  more  rapidly 
and  definitely  with  bacteria  than  with  protozoa. 
Bacterial  life  and  activity  can  be  controlled  very 


20     PLACE  OF  MICROORGANISMS  IN  NATURE 

largely  now,  but  as  yet  little  or  nothing  is  known  of 
the  important  vital  activities  of  the  minute  animals. 

As  in  the  case  of  bacteria  so  the  earliest  records  of 
protozoa  are  those  of  Van  Leeuwenhoek's  animalculse. 
Their  natural  history  has  been  gradually  developed 
by  Jablot,  Dujardin,  and  Biitschli,  and  the  present 
leaders  in  the  field — Calkins,  Doflein,  and  Prowaczek. 
However,  it  is  only  within  the  last  score  of  years  that 
we  have  been  familiar  enough  with  these  lowest  animal 
forms  to  be  sure  of  their  species  identity,  and  we  are 
imperfectly  informed  as  to  their  vital  phenomena. 

PLACE  OF  MICROORGANISMS  IN  NATURE 

The  studies  of  the  life  history  of  bacteria  and  pro- 
tozoa have  been  the  work  of  botanists,  chemists,  and 
physicians.  Through  this  combined  effort  it  has 
become  known  that  these  minute  forms  are  present 
in  or  upon  or  have  something  to  do  with  the  life  of  all 
the  higher  animals  and  plants.  The  number  of  species 
in  all  is  legion.  The  number  of  species  pathogenic 
for  animals  is  but  small.  A  microorganism  is  patho- 
genic when  it  is  capable  of  producing  some  form  of 
disease  in  the  animal  in  which  it  is  a  parasite  In 
Chapter  III  some  of  the  known  relations  of  non- 
pathogenic  bacteria  will  be  discussed.  It  is  sufficient 
here  to  emphasize  the  difference  between  the  so-called 
parasites  and  saprophytes.  Parasites  are  bacteria 
capable  of  living  and  multiplying  within  the  living, 
animal  body,  sometimes  to  its  detriment,  while  the 
saprophytes  live  on  dead  matter  and  may  be  found  in 
nature  everywhece,  in  air,  soil,  water.  The  body  upon 


PLACE  OF  MICROORGANISMS  IN  NATURE     21 

which  a  parasite  lives  is  called  the  host.  There  are  a 
few  of  the  parasites  that  can  carry  on  a  saprophytic 
existence  for  a  short  time  (facultative  parasites),  while 
others  (obligate  parasites),  such  as  the  organism  of 
influenza,  require  animal  juices  for  their  nutriment. 
Among  the  protozoa  this  obligate  parasitism  exists 
quite  extensively.  Many  forms  cannot  live  at  all  if 
their  normal  cycle  of  life  within  the  animal  body  be 
disturbed.  The  saprophytes  include  the  vast  number 
of  organisms  having  important  functions  among  the 
higher  vegetables  and  the  growth  of  these  in  soil.  It 
has  been  suggested  that  at  one  time,  now  long  past, 
all  bacteria  might  have  been  saprophytic. 

The  general  remarks  concerning  parasites  apply 
alike  to  protozoa  and  bacteria,  but  in  medicine  there  is 
at  the  present  time  more  interest  in  the  bacteria.  For 
this  reason  only  a  few  diseases  caused  by  protozoa  are 
important. 

In  order  that  the  positions  these  unicellular  forms 
occupy  in  the  living  world  may  be  known  and  used 
for  reference  to  large  works,  their  biological  classifica- 
tion is  given  here.  The  lowest  of  the  orders  among  the 
plants  is  called  Thallophyta.  This  is  divided  into 
Algse,  Lichens,  and  Fungi.  The  Fungi  are  divided 
into  Hyphomycetes  (moulds),  Blastomycetes  (yeasts), 
and  Schizomycetes  (bacteriaceae  or  bacteria).  This 
family  is  divided  into  Cocci,  Bacilli,  and  Spirilla. 

Protozoa,  the  lowest  animal  class,  present  the  orders 
Sarcodina,  Mastigophora,  and  Sporozoa,  which  con- 
tain nearly  all  the  forms  of  interest  in  this  work. 


CHAPTER    II 

GENERAL  MORPHOLOGY— REPRODUCTION- 
CHEMICAL  AND  PHYSICAL  PROPERTIES 

GENERAL  MORPHOLOGY 

Bacteria  (sing.,  Bacterium). — In  introducing  the  sub- 
ject of  morphology  a  few  words  as  to  the  technique  of 
observing  bacteria  will  not  be  amiss.  The  compound 
microscope  is  necessary  to  all  microbiological  work. 
Since  this  book  is  devoted  to  principles,  a  detailed 
description  of  the  instrument  and  its  operations  would 
be  foreign.  Let  it  suffice  to  say  that  the  compound 
microscope  is  a  series  of  finely  ground  lenses  by  which 
exact  pictures  in  definite  magnification  can  be  obtained. 
An  object  to  be  examined  is  placed  upon  a  glass  slide 
and  covered  with  another  but  much  thinner  glass  cover. 
This  is  laid  upon  the  table  of  the  instrument  and  the 
tube  holding  the  lens  placed  at  a  proper  distance  to 
obtain  the  best  light  and  clearest  picture  when  viewed 
through  the  eye-piece  end.  For  nearly  all  microbiologi- 
cal observations  it  is  advisable  to  introduce  between  the 
object  glass  and  the  lens  a  drop  of  pure  cedar  oil  in 
order  that  light  can  be  made  pure  and  concentrated. 
The  microscope  is  also  used  to  examine  the  colonies 
of  bacteria.  Bacteria  are  studied  either  in  the  fresh 
living  condition  or  when  stained  by  appropriate  dyes. 

Bacteria  are  exceedingly  small  single  cells,  in  their 


GENERAL  MORPHOLOGY 


23 


natural  state  transparent,  colorless,  and  apparently 
homogeneous,  possessing  a  very  low  power  of  refracting 
light.  They  consist  of  a  wall  which  is  probably  a 


FIG    1 


Microscope:  A,  ocular  or  eye-piece;  B,  objective;  C,  stage;  D,  "iris"  dia- 
phragm; E,  reflector;  F,  coarse  adjustment;  O,  fine  adjustment;  H,  sub-stage 
condensing  apparatus;  /,  nose-piece. 


24  GENERAL  MORPHOLOGY 

simple  condensation  of  the  interior.  The  ordinary 
animal  or  vegetable  single  cell1  contains  an  easily  dis- 
tinguishable body,  usually  central,  called  the  nucleus, 
whose  function  it  is  to  control  the  cell  activities, 
while  the  space  between  this  body  and  cell  wall  is 
occupied  by  protoplasm  or  cytoplasm.  Into  this 
cytoplasm  the  nourishment  of  the  cell  passes.  Of 
bacteria,  either  in  their  natural  condition  or  stained 
for  examination,  only  the  nucleus  and  the  wall  can 
be  seen,  the  intervening  layer  being  exceedingly  thin. 


FIG.  2 


o 
a 

OD 


a,  staphylococci;  b,  streptococci;  c,  diplococci;   <7,  tetrads;   e,  sarcinse. 
(Abbott.) 

In  shape,  bacteria  are  either  spherical,  called  cocci 
(sing.,  coccus),  or  straight  rods,  called  bacilli  (sing., 
bacillus),  or  curved  rods,  called  spirilla  (sing.,  spiril- 
lum). Each  shape  has  slight  variations,  such  as  the 
flattening  of  the  sides  when  two  organisms  are  apposed. 
The  spirilla  are,  perhaps,  subject  to  more  variations 


1  See  frontispiece  for  an  example  of  cell.     Nearly  all  living  calls  are  com 
parable  to  these  leukocytes. 


GENERAL  MORPHOLOGY  25 

than  the  others,  extending  from  a  simple  comma  shape 
to  that  of  a  long  wavy  spiral  when  looked  at  from  the 
side.  These  last  are  in  reality  corkscrews,  as  they  twist 
in  three  planes.  In  size  microorganisms  vary  consider- 
ably. Perhaps  a  proper  conception  of  some  organisms 


FIG.  3 


-^ 

<^>w     V 


a,  bacilli  in  pairs;  b,  single  bacilli;  c  and  d,  bacilli  in  threads;  e  and  /, 
bacilli  of  variable  morphology.     (Abbott.) 

FIG.  4 


o  b  c  •    d 

a  and  d,  spirilla  in  short  segments  and  longer  threads — the  so-called 
comma  forms  and  spirals;  b,  the  forms  known  as  spirochsetse,  c,  the  thick 
spirals  sometimes  known  as  vibrios.  (Abbott.) 

can  be  obtained  when  one  considers  that  to  cover  one 
square  inch  in  single  layer  it  would  require  6,250,000,000 
influenza  bacilli,  a  very  small  organism,  or  45,000,000 
anthrax  bacilli,  a  bacterium  of  moderate  size.  Bac- 
teria are  measured  in  terms  of  microns.  The  metric 
unit,  a  micron,  equals  about  2TTro^r  °f  an  inch. 


26  SPECIAL  CHARACTERS 

REPRODUCTION 

Bacteria. — Bacteria  multiply  by  a  simple  dividing 
of  their  protoplasm.  The  spherical  organisms  divide 
much  as  one  cuts  an  apple  through  the  poles,  the 
divided  halves  rapidly  assuming  the  shape  of  the 
mother  cell.  The  rods  and  spirals  divide  by  simple 
transverse  pinching  in  at  about  the  middle  of  their 
long  axis. 

The  new  forms  may  leave  each  other  or  may  adhere 
in  more  or  less  characteristic  groupings,  which  are 
taken  advantage  of  in  their  study  and  identification. 
Thus  cocci  may  form  pairs  or  chains  and  are  known  as 
diplo-  or  streptococci.  Again,  the  spheres  may  pro- 
duce irregular  grape-like  bunches  or  staphylococci. 
These  develop  in  only  two  planes.  Division  may 
occur  in  the  third  plane  so  that  packets  or  cubes  of 
cells  result,  called  sarcinse.  Among  the  rod-shaped 
bacilli  long  chains  may  be  formed  by  a  continuous 
development  in  the  same  plane. 

A  single  bacterial  cell  will  divide  about  every  twenty 
minutes,  and  Fischer  says  that  from  one  organism 
16,000,000,000  may  develop  in  a  single  day  on  suitable 
medium. 

SPECIAL  CHARACTERS 

The  cell  is  sometimes  surrounded  by  an  envelope 
or  capsule  and  this  is  taken  advantage  of  in  identi- 
fication. It  is  particularly  well  developed  on  bacteria 
while  in  or  lately  removed  from  animal  tissues  upon 
which  they  have  been  growing.  The  exact  function 
or  importance  of  these  capsules  is  not  known. 


SPECIAL   CHARACTERS 


27 


Some  bacteria  are  able  to  move  from  place  to  place 
in  a  fluid  medium.     This  is  due  to  the  presence  of 


FIG.  5 


Capsule  stain  by  Hiss'  method.     Rhinoscleroma  bacillus.     X  1000.     (Thro.) 

FIG.  6 


XV 

A 


Bacilli  showing  one  polar  flagellum.     (Park.) 

extremely  fine  filamentous  extensions  from  the  cell 
wall,  which  upon  microscopic  examination  look  like 


28 


SPECIAL  CHARACTERS 


wavy  hairs.     These  are  called  flagella   (sing.,  flagel- 
lum).     They  are  arranged  either  at  one  end,  both 


FIG.  7 


Bacilli  showing  multiple  flagella.     (Park.) 
FIG.  8 


Unstained  spores  in  slightly  distended  bacilli.     (The  spores  are  the  light 
oval  spaces  in  the  heavily  stained  bacilli.)     (Park.) 

ends,  or  around  the  whole  surface  of  the  cell.  They 
propel  the  bacterium  by  a  quick  waving  or  lashing 
motion. 


SPECIAL  CHARACTERS  29 

When  bacteria  are  subjected  to  conditions  unfavor- 
able for  their  life  they  undergo  various  changes  of 
size  and  shape,  none  of  which  are  very  characteristic 
except  the  so-called  spore  formation.  By  this  is 
meant  the  concentration  of  the  vital  powers  and  some 
of  the  physical  constituents  of  the  bacterial  cell  within 
a  very  small,  homogeneous,  highly  light-refractive 
body  which  is  resistant  to  deleterious  agencies  and 
which  mav  bear  little  or  no  resemblance  to  the  parent 


FIG.  9 


Unstained  spores  in  distended  ends  of  bacilli.     (Park.) 

organism.  These  spores  are  not  to  be  considered  as 
evidences  of  reproduction,  but  merely  as  a  resting  or 
resistance  stage.  When  conditions  of  life  suitable  to 
the  normal  appearance  of  the  bacterium  are  resumed, 
the  spore  will  develop  into  the  same  kind  of  organism 
as  that  from  which  it  came.  This  spore  forming  is  seen 
among  bacilli  and  spirilla,  probably  never  among  the 
cocci.  As  a  rule,  only  one  spore  is  found  in  each 
bacterial  cell.  These  spore  formations  assist  in  identi- 
fication. The  practical  importance  of  spores  is  that 


30  SPECIAL  CHARACTERS 

they  resist  the  agencies  quickly  fatal  to  the  adult 
forms.  Bacteria  in  their  ordinary  development  are 
said  to  be  vegetating,  and  we  must  differentiate 
between  the  vegetative  stage  and  the  spore-forming 
stage. 

Protozoa  (sing.,  Protozoan). — Protozoa  are  single-cell 
animals  of  protean  shape.  They  vary  in  size  from  that 
of  the  smallest  bacterium  to  nearly  one-quarter  of  an  inch 
in  length.  They  are  made  up  of  a  fairly  well-formed  wall 
which  may  have  an  appreciable  thickness  or  be  merely 
an  immeasurable  line.  Their  cytoplasm,  unlike  that  of 
bacteria,  is  usually  far  in  excess  of  the  nucleus.  It  is 
sometimes  homogeneous,  at  other  times  full  of  granules, 
septa,  or  a  dividing  mesh  work.  The  nucleus  is  a  com- 
plex body  varying  from  a  simple  bladder-like  mass  to  a 
dense  and  intricately  wound  skein.  The  vital  activity 
of  the  protozoan  cell  seems  to  lie  in  a  small  body 
usually  in  the  protoplasm,  but  originating  from  the 
nucleus,  called  the  centresome.  Protozoa  move  by 
several  methods.  Some  possess  short,  delicate,  hair- 
like  projections  from  the  wall  which  exhibit  a  slow, 
wavy  motion.  These  are  cilia.  Others  have  one,  two 
or  three  long  coarser  threads,  the  flagella  (sing., 
flagellum)  arising  from  various  parts  of  the  struc- 
ture and  producing  locomotion  by  a  thrashing  or 
whip-like  motion.  Perhaps  the  simplest  and  surely 
the  most  primitive  form  of  motion  is  to  be  seen 
in  what  are  called  pseudopods  or  false  feet,  a  phe- 
nomenon characteristic  of  the  amebse.  This  is  a 
pushing  out  or  budding  of  a  portion  of  the  cell  wall 
into  which  the  cytoplasm  of  the  protozoon  flows, 
enlarging  the  false  foot  until  it  embraces  all  the  con- 


CHEMICAL  AND  PHYSICAL  PROPERTIES     31 

tents  of  the  cell.  The  space  formerly  occupied  by 
the  protozoon  is  vacated  and  it  has  moved  to  a  position 
directed  by  the  pseudopod.  In  some  protozoa  a 
portion  of  the  body  has  muscular  power  and  drives  the 
body.  Again,  a  portion  of  the  cell  wall  may  be  fitted 
with  a  sucking  apparatus,  serving  both  to  drive  or  to 
attach  the  protozoon  to  another  body.  They  gain 
their  food  by  simple  absorption  through  the  wall  or  by 
possessing  definite  vacuoles  or  openings  for  this  pur- 
pose. Excretion  takes  place  the  same  way. 

Reproduction  may  occur  by  simple  dividing  as  in 
bacteria.  Protozoa  may  divide  by  simple  budding 
with  breaking  off  of  the  smaller  piece  similar  in  the 
first  stages  to  the  pseudopod.  The  higher  protozoa 
go  through  a  complicated  process  of  division  such  as 
is  seen  in  the  higher  animal  cells,  or  there  may  be 
male  and  female  elements  with  conjugation. 

CHEMICAL  AND  PHYSICAL  PROPERTIES 

Bacteria. — Chemically  the  bacterial  body  is  composed 
chiefly  of  water  (80  to  90  per  cent.),  the  remaining 
part  being  made  up  of  proteid  (see  below),  fatty  matters, 
including  waxes,  a  trace  of  the  carbohydrates  (sugars 
and  starches),  and  inorganic  material.  The  cellulose 
supposed  to  be  characteristic  of  vegetable  cells  is 
present  in  very  small  quantities.  The  largest  part  of 
the  solid  matter  is  comparable  to  the  organic  sub- 
stances which  form  the  most  important  foodstuff  for 
animals,  the  proteids.  Chlorides  and  phosphates  of 
the  lighter  metals  form  the  inorganic  salts. 

The  wall  of  the  bacterial  cell  permits  the  passage 


32     CHEMICAL  AND  PHYSICAL  PROPERTIES 

of  fluids  containing  foodstuffs,  and  is  therefore  com- 
parable to  the  wall  of  other  vegetable  and  animal  cells. 
Protozoa. — The  chemical  composition  is  probably 
like  that  of  bacteria,  although  little  is  known  of  it. 
Their  vital  activities  are  influenced  by  physical  con- 
ditions, as  is  the  case  with  all  animate  beings.  They 
require  moisture  for  their  full  development,  but  may 
live  for  indefinite  times  when  it  is  at  a  minimum.  A 
definite  temperature  is  demanded  by  each  species  or 
genus  for  its  full  activity.  They  are  susceptible  to 
high  degrees  and  remain  quiescent  in  nature  in  the  cold 
for  a  long  time.  Desiccation  of  the  germinating  forms 
is  usually  fatal,  but  when  in  sporulation  or  encystment 
drying  is  more  easily  withstood.  Light  is  not  abso- 
lutely essential  for  the  growth  of  protozoa,  but  they 
are  usually  attracted  or  repelled  by  it;  that  is,  few 
if  any  are  indifferent  to  luminosity. 


CHAPTER   III 

GENERAL    BIOLOGY,    INCLUDING    THE 

CHEMICAL  CHANGES  WROUGHT 

BY  BACTERIA 

Bacteria. — The  bacteria  with  which  the  physician  is 
chiefly  concerned  as  disease-producing,  are  but  a  very 
small  number  when  compared  with  the  multitude  of 
species  in  nature.  The  lay  mind  is  apt  to  consider  any 
germ  as  noxious,  but  instead  of  this  it  can  be  said  that 
without  the  activity  of  many  saprophytes,  life  on  the 
earth  would  soon  be  extinct.  Animals  require  organic 
material  for  their  nourishment,  but  their  cells  do  not 
possess  the  power  to  put  together  (synthesize)  the 
elementary  constituents  necessary  for  their  complex 
cell  composition.  Bacteria  have  the  power  both  of 
breaking  down  and  building  up;  that  is,  they  may 
reduce  some  compounds  to  their  elements  or  build 
up  elements  into  more  complex  substances. 

The  products  of  their  breaking  down  and  building 
up  are  utilized  by  plants  and  are  presented  to  animals 
as  food  in  such  a  form  that  the  animals  can  use  them 
for  their  cell  needs.  It  is  not  the  purpose  of  this  book 
to  dwell  upon  this  abstract  matter  of  general  biology, 
but  the  principles  of  the  activities  of  non-pathogenic 
bacteria  can  well  be  seen  in  those  inhabiting  the 
intestines. 

It  may  be  possible  for  a  human  being  to  live  without 
3 


34  GENERAL  BIOLOGY 

bacteria  in  the  alimentary  tract,  but  some  of  those 
present  are  beneficial  in  effect.  They  gain  access  in  the 
food  and  air.  They  assist  in  making  fats  more  easily 
assimilable,  and  they  destroy  some  of  the  pathogenic 
bacteria.  Incidentally  it  might  be  added  that  their 
activity  in  producing  excessive  putrefaction  and  fer- 
mentation may  be  harmful  to  the  body  in  general. 

Bacteria  require  for  their  life  moisture,  some  degree 
of  heat,  and  a  variety  of  foodstuffs. 

The  reaction  of  the  material  upon  which  they  are 
growing  is  of  no  small  importance.  Nearly  all  bacteria 
live  best  when  the  medium  is  about  neutral  or  of 
faintly  alkaline  or  acid  reaction.  All  need  carbon, 
oxygen,  nitrogen,  hydrogen,  and  salts.  Some  organisms 
cannot  live  in  the  presence  of  free  oxygen,  but  obtain 
it  as  they  need  it  by  breaking  up,  or  reducing,  sub- 
stances containing  this  element.  These  are  called 
anaerobic  bacteria,  such  as  the  tetanus  bacillus.  Micro- 
organisms that  can  live  in  the  presence  of  atmospheric 
oxygen  are  called  aerobic.  Most  pathogenic  forms  have 
this  power. 

The  foodstuffs  presented  to  bacteria  are  seldom  in  a 
pure  state,  so  that  the  power  of  breaking  up  the 
material  on  which  they  are  existing  into  the  elements 
necessary  for  the  life  of  the  cell  has  to  be  done  by  some 
process  of  cellular  activity.  To  do  this,  bacteria  form 
what  are  called  enzymes  or  ferments.  An  enzyme  or 
ferment  is  a  product  capable  of  changing  a  chemical 
combination  without  itself  entering  into  the  product 
of  this  change.  The  bacterial  enzymes  are  comparable 
to  the  enzymes  found  in  the  digestive  juices  of  the 
human  alimentary  canal.  There  are  many  kinds  of 


CHEMICAL  CHANGES  WROUGHT  BY  BACTERIA     35 

ferments,  each  having  the  power  of  breaking  up  certain 
chemical  substances.  There  are  ferments  splitting  up 
sugars  and  starches  and  fats  and  proteids,  and  the 
result  of  this  splitting  is  simpler  in  composition  than 
the  substance  split,  thus  making  it  easier  of  use  as 
food.  Advantage  is  taken  of  these  bacterial  ferments 
in  the  industries,  especially  that  of  spirituous  liquor- 
making.  In  this  case  the  bacteria  and  their  enzymes 
are  capable  of  splitting  sugar  with  the  production  of 
ethyl  alcohol,  and  specific  species  or  strains  are  kept 
by  vineyards,  distilleries,  and  breweries  for  the  peculiar 
kind  of  fermentation  desired. 

Some  bacteria  have  the  property  of  producing  light, 
and  many  form  coloring  matter  both  in  nature  and 
when  grown  artificially. 

The  effect  of  saprophytes  upon  pathogenic  bacteria 
in  the  intestine  is  that  they  sometimes  destroy  the 
latter.  Metchnikoff  found  that  certain  bacteria  pro- 
duced so  much  acid,  chiefly  lactic  acid,  that  many 
other  bacteria  could  not  live  in  their  presence.  He 
took  advantage  of  this  to  assist  in  the  treatment  of 
certain  cases  of  putrefaction  in  the  intestinal  tract. 
Bacteria  also  may  produce  various  simpler  products  in 
the  course  of  their  enzyme  action.  Now  it  happens 
that  some  of  the  bacteria  in  the  intestinal  tract,  per- 
haps under  the  stimulation  of  irregularity  of  function, 
may  produce  too  much  fermentation  of  sugars  and 
starches  or  too  great  breaking  down  of  the  most 
important  foodstuff,  the  proteids.  From  this  improper 
breaking  down  and  absorption  of  its  products  comes 
the  so-called  auto-intoxication.  Metchnikoff 's  experi- 
ments have  shown  that  the  high  acid  produced  by 


36  GENERAL  BIOLOGY 

certain  saprophytes,  the  lactic  acid  germs  in  particular, 
is  inimical  to  the  producers  of  this  disturbance.  In 
practice,  therefore,  cultures  of  these  bacteria  are 
administered  by  mouth. 

Other  activities  of  bacteria  and  their  enzymes  are 
seen  in  the  precipitation  and  curdling  of  cream,  known 
as  cheese.  Again,  the  specific  flavor  of  tobacco  and 
opium  for  the  pipe  is  due  to  bacteria.  In  the  pro- 
duction of  indigo  and  in  the  preparation  of  hides  for 
tanning  bacterial  enzymes  play  an  important  part. 

Protozoa. — Of  the  saprophytes  of  protozoa  practically 
nothing  is  known.  Protozoa  are  parasitic  either  by  the 
mechanical  irritation  caused  by  their  pressure  or  by 
taking  their  nutriment  to  the  damage  of  their  host. 
For  optimum  development  they  require,  as  in  the 
case  of  bacteria,  moisture  and  a  suitable  reaction, 
but  rather  a  higher  temperature  and  more  complicated 
food,  as  a  rule. 


CHAPTER   IV 

METHODS  OF  STUDYING  MICROORGANISMS 
-STERILIZATION  BY  HEAT 

LABORATORY  TECHNIQUE 

IN  the  study  of  microscopic  beings,  it  has  been 
necessary  to  elaborate  a  special  technique  which  will 
supply  the  requirements  of  life.  Before  the  epoch- 
making  work  of  Koch  it  was  necessary  to  cultivate 
microorganisms  upon  broth  or  bread,  and  there  wyas 
little  known  as  to  the  exact  composition  of  the  medium. 
Koch  showed  how  to  control  the  growth  of  bacteria 
in  the  laboratory.  To  Pasteur  and  Kohn  also  is  due 
credit  for  the  standardizing  of  the  foodstuffs  upon 
which  bacteria  are  cultivated.  Let  us  assume  that'  we 
have  been  given  a  culture  of  bacteria  to  study.  Since 
the  identification  of  species  is  not  a  part  of  a  nurse's 
duty  it  is  not  necessary  to  discuss  the  separation  of 
many  germs  in  a  mixture.  Bacteria  are  transferred 
from  one  place  to  another,  as,  for  example,  from  one 
culture  tube  to  another  or  to  a  glass  slide  by  means  of 
a  piece  of  platinum  wire  set  into  a  handle.  This  metal 
will  withstand  great  heat  and  can  be  sterilized  in  the 
flame  of  a  Bunsen  burner  after  every  using.  The 
Bunsen  burner  is  an  apparatus  so  arranged  that  air  is 
thoroughly  mixed  with  the  gas  and  the  mixture  is 
completely  burned,  Starting  out  with  the  material 


38      METHODS  OF  STUDYING  MICROORGANISMS 

from  which  this  single  organism  comes  the  bacteri- 
ologist colors  it  by  certain  aniline  or  vegetable  dyes, 
of  which  there  are  a  large  number.  It  is  practically 
impossible  certainly  to  identify  any  bacterium  by  a 

FIG.  10 


Showing  certain  macroscopic  characteristics  of  colonies.     Natural  size. 
(Abbott.) 

simple  examination  of  a  stained  preparation  under 
the  microscope.  The  observer,  however,  does  form  a 
tentative  opinion  as  to  its  probable  nature,  and  pro- 
ceeds to  introduce  some  of  the  material  into  a  nutrient 
medium  which  he  considers  best  adapted  to  its  develop- 


LABORATORY  TECHNIQUE  39 

ment.  Among  these  are  broth,  milk,  potato,  coagu- 
lated blood  serum,  and  broth  stiffened  (when  cool) 
with  gelatine  and  the  Japanese  moss,  agar-agar.  These 
foodstuffs,  called  media  for  short  (sing.,  medium)  are 

FIG.  11 


Platinum  needle  and  loop.      (Park.) 

kept  in  test-tubes  or  flasks.  He  may  also  spread  into 
flat  glass  plates  (Petri  plates)  some  of  this  stiffened 
broth  in  order  first  to  see  in  what  form  the  germs  will 
grow  as  "colonies,"  and  secondly  to  see  that  only  one 
kind  of  colony,  therefore  only  one  kind  of  germ,  is 
present.  In  other  words,  he  wishes  to  know  if  his 
culture  be  "pure."  These  tubes  and  plates  are  placed 


40     METHODS  OF  STUDYING  MICROORGANISMS 

at  body  temperature  (98°  F.  or  37.5°  C.)  in  the  incu- 
bator. An  incubator  is  a  doubly  insulated  metal  box, 
heated  by  gas  or  electricity  and  controlled  by  an 
automatic  device  by  which  the  temperature  is  kept 
constantly  where  desired.  Practically  all  pathogenic 

FIG.  12 


Method  of  transferring  cultures  from  one  tube  to  another.     (Hiss  and  Zinsser.) 

bacteria  develop  best  at  this  temperature.  The 
bacteria  of  the  soil  and  water  probably  grow  best  at 
about  70°  F.  or  20°  C.  After  these  tubes  and  plates 
have  been  "incubated"  for  twenty-four  or  forty-eight 
hours  the  bacteriologist  observes  them  and  takes  note 
of  the  evidences  of  growth.  He  will  make  stained 


LABORATORY  TECHNIQUE  41 

preparations  for  microscopic  observation  and  note  the 
morphology  of  the  plant.  Many  stains  are  in  use  for 
demonstrating  various  characteristics.  He  will  also 
prepare  what  is  known  as  a  "hanging  drop/'  This 
consists  of  a  drop  of  fluid  broth  culture  upon  a 
thin  inverted  glass  (Fig.  13).  He  will  discover  from 
this  preparation  under  the  microscope  the  presence  of 
motility  and  the  manner  of  division  of  the  bacteria. 
From  his  tube  cultures  he  chiefly  finds  out  whether 
the  bacteria  develop  enzymes.  To  the  solid  media 
(agar-agar)  he  may  add  various  sugars  to  discover  the 
fermentative  powers  of  the  bacterium.  The  fermenta- 
tive powers  may  also  be  observed  when  the  germs  grow 

FIG.  13 


Hollow  slide  with  cover-glass.    (Park.) 

upon  bouillon  containing  the  sugars.  This  broth  is 
placed  in  an  apparatus  called  fermentation  tubes,  so 
arranged  that  the  percentage  of  sugar  broken  up  by 
the  bacteria  can  be  estimated.  When  he  shall  have 
made  all  his  observations  he  will  sum  up  his  results 
and  identify  according  to  the  classification  of  bac- 
teriologists. 

Animal  Inoculation. — Another  method  of  studying 
bacteria  is  by  injecting  them  into  susceptible  animals. 
Thus  can  be  discovered  their  power  of  producing 
disease,  its  severity,  called  virulence,  and  the  nature 
of  their  action.  Animal  inoculation  is  used  for  keeping 
alive  certain  viruses  or  increasing  the  virulence  of 
those  whose  strength  has  declined.  When  the  presence 


42     METHODS  OF  STUDYING  MICROORGANISMS 

of  bacteria  cannot  be  demonstrated  by  stain  or  cultural 
methods,  it  may  sometimes  be  shown  by  injecting  the 
suspected  material  into  animals.  If  the  animal  fall 
sick  or  die  one  can  then  obtain  the  germs  for  study. 
It  is  most  useful  in  discovering  the  presence  of  the 
tubercle  bacillus,  an  organism  not  easy  to  find  by 
direct  examination. 

Protozoa. — The  study  of  protozoa  varies  according 
to  the  source.  The  parasite  of  malaria  may  be  found 
by  direct  microscopic  examination  of  the  fresh  blood. 
This  is  also  true  of  the  organism  of  sleeping  sickness. 
The  protozoa  causing  dysentery  require  the  mainte- 
nance of  a  definite  temperature  for  a  long  time,  and 
this  is  achieved  by  the  use  of  a  hollow  slide  filled  with 
warm  water.  These  organisms  are  cultivated  arti- 
ficially only  with  great  difficulty,  and  the  use  of  special 
stains  is  required  for  the  purpose  of  practical  clinical 
diagnosis. 

STERILIZATION 

For  a  better  understanding  of  the  technique  of 
laboratory  procedure,  the  preparation  of  the  food- 
stuffs or  media  on  which  bacteria  thrive  will  be  briefly 
considered.  They  are  prepared  according  to  carefully 
worked-out  formulae,  which  are  the  result  of  long 
experimentation.  They  are  stored  or  distributed  in 
glassware,  which  is  of  the  non-corrosive  type.  This 
glassware  is  cleaned  with  soap  and  water,  sand  or 
alcohol,  and  rinsed  with  distilled  water.  It  is  then 
sterilized  by  hot  air.  The  glassware  and  media  are 
sterilized  because  bacteria  are  ubiquitous  and  appa- 
ratus and  foodstuffs  wholly  free  from  microorganisms 


STERILIZATION 


43 


are  necessary  in  bacteriological  technique.    In  no  other 
way  can  one  be  sure  of  obtaining  germs  in  pure  culture, 


FIG.  14 


FIG.  15 


FIG.  16 


A  B 

Autoclave,  pattern  of  Wiesnegg:    A,  external  appearance:    B,  section. 


44      METHODS  OF  STUDYING  MICROORGANISMS 

that  is,  only  one  kind.  After  the  glassware  contains  the 
medium,  which  is  destroyed  by  dry  heat,  steam  sterili- 
zation is  used.  The  best  method  of  sterilization  is  by 
the  autoclave  or  pressure  boiler,  since  all  organisms  are 
killed  by  one  atmosphere  of  pressure  to  the  square 
inch  in  addition  to  the  ordinary  atmospheric  pressure. 
Because  of  the  delicacy  of  some  of  the  nutrient  media, 
it  is,  however,  necessary  to  sterilize  these  at  the  usual 

FIG.  18 


Arnold  steam  sterilizer. 


pressure  of  the  atmosphere  in  streaming  steam.  For 
this  purpose  a  double  jacketed  boiler  with  the  steam 
introduced  into  the  inner  chamber  (Arnold  steam 
sterilizer)  is  used. 

While  this  sufficiently  indicates  the  uses  of  sterili- 
zation for  the  preparation  of  food  for  bacteria,  a  few 
words  upon  sterilization  in  general  are  necessary. 
This  term  is  usually  reserved  for  the  killing  of  bacteria 


STERILIZATION  45 

by  means  of  heat,,  either  dry  or  moist.    For  the  killing 
of  bacteria  by  other  means  see  Chapter  V. 

The  most  widely  applicable  and  efficient  physical 
agent  for  sterilization  is  heat.  A  certain  amount  of 
heat  is  necessary  for  the  life  of  bacteria,  but  there  are 
certain  temperatures  beyond  which  they  cease  to  live. 
While  38°  C.  or  98.5°  F.  is  their  optimum,  they  find  it 

FIG.  19 


Laboratory  hot-air  sterilizer. 

increasingly  difficult  to  live  as  the  temperature  rises 
to  50°  C.  or  122°  F.  Beginning  there  and  extending  to 
62°  C.  or  144°  F.  the  commoner  pathogenic  organisms 
are  killed  by  ten  minutes'  exposure.  For  example,  the 
typhoid  bacillus  dies  when  heated  to  56°  C.  or  133°  F. 
for  ten  minutes,  the  pneumonia  coccus  at  52°  C.  or 
126°  F.  for  ten  minutes.  The  tubercle  bacillus  is  much 
more  resistant,  and  requires  from  ten  to  twenty  minutes' 


40      METHODS  OF  STUDYING  MICROORGANISMS 

exposure  at  70°  C.  or  158°  F.,  varying  directly  with  the 
density  of  the  medium  in  which  it  is.  The  spore-forming 
organisms  are  characterized  by  a  vastly  greater 
resistance.  This  is  due  to  the  peculiar  property  of 
spores  of  resisting  deleterious  agencies. 

Low  temperatures  are  much  less  destructive  than 
high  ones.  The  typhoid  and  diphtheria  organisms  may 
resist  200°  below  zero  C.  or  —300°  F.,  while  some  of  the 
more  delicate  organisms  quickly  die  at  zero.  In  sterili- 
zation that  method  is  chosen  which  will  do  the  least 
damage  to  any  object  to  be  conserved.  Simple  boiling 
should  be  undertaken  whenever  practicable,  and  immer- 
sion for  five  minutes  in  boiling  water  will  destroy  the 
vegetative  forms  of  all  bacteria.  For  spores,  however, 
at  least  of  the  disease-producing  kind,  two  hours  is 
necessary.  It  is  advisable  to  add  1  per  cent,  of  sodium 
carbonate  to  the  water.  This  assists  in  killing  of  spores 
and  metal  objects  are  not  so  apt  to  rust.  This  simple 
boiling  for  ten  minutes  is  sufficient  for  dry  cleaned 
syringes  and  surgical  instruments  in  the  absence  of 
infective  material  known  to  contain  spores.  Steriliza- 
tion in  live  steam  is  the  most  practical  method  of 
killing  bacteria,  as  it  can  be  carried  out  in  the  kitchen. 
In  the  laboratory  it  is  done  by  the  Arnold  sterilizer 
(Fig.  18).  It  is  the  custom  to  employ  what  is  called 
fractional  sterilization.  This  method  is  the  exposure 
of  the  material  to  be  disinfected  to  the  temperature  of 
100°  C.  or  212°  F.,  which  is  the  temperature  reached  by 
the  steam  in  the  inner  chamber,  for  fifteen  minutes  on 
three  successive  days.  On  the  first  occasion  vegetative 
forms  are  killed  and  the  spores  remaining  are  permitted 
to  pass  into  the  vegetative  state  over  night.  On  the 
second  occasion  these  will  then  be  killed.  A  third  ex- 


STERILIZATION  47 

posure  insures  sterility.  The  exposure  of  fifteen  min- 
utes is  considered  to  begin  when  the  steam  is  up  and 
the  thermometer  registers  100°.  For  sterilization  of 
objects  not  injured  by  pressure  the  boiler  or  autoclave 
is  used.  By  this  means  as  much  as  two  extra  atmos- 
phere pressures  can  be  run  up,  which  will  be  equivalent 
to  34.5°  C.  or  74°  F.  above  the  boiling  point.  After 
starting  up  steam  the  apparatus  should  never  be  tightly 
closed  at  the  safety  valve  until  all  air  is  expelled.  This 
method  is  particularly  adapted  to  the  sterilization  of 
dressings  and  infected  cast-off  clothing.  Hot  air  is 
suitable  for  dried  glassware  and  articles  injured  by 
moisture.  It  is  less  efficient  than  moist  heat.  This 
is  due  to  the  fact  that  organic  substances  are  less 
easily  coagulated  in  a  dried  condition.  Spores  are 
more  resistant  also,  as,  for  example,  the  anthrax 
spore,  which  requires  an  exposure  of  three  hours  at 
140°  C.  or  284°  F.  dry  heat.  Hot  dry  air  penetrates 
less  easily  than  hot  moisture.  Burning  is  best  of  all 
methods. 

The  two  thermometric  scales  are  explained  as  follows: 

F  =  Fahrenheit,  the  ordinary  scale  used  in  this  country.  Water 
just  at  the  freezing  point  registers  32°  F.,  while  just  at  the  boil- 
ing point  registers  212°  F.  The  zero  has  no  relation  to  physical 
changes. 

C  =  Centigrade,  the  French  system.  Water  just  at  the  freezing 
point  is  0°  C.,  and  just  at  boiling  point  is  100°  C. 

The  100°  in  the  Centigrade  scale  is  equal  to  the  180°  in  the 
Fahrenheit  scale,  between  32°  and  212°. 

To  change  one  system  to  the  other  proceed  as  follows  : 

From  Fahrenheit  to  Centigrade:  Given  degree  F.  — 32  -i-9  X5  = 
same  degree  in  Centigrade  scale.  Example:  50°  F.  — 32  =  18 -j- 9  = 
2X5  =  10.  Therefore  50 °  F.  =  10 °  C. 

From  Centigrade  to  Fahrenheit :  Given  degree  C.  -J- 5  X 9 +32  = 
same  degree  in  Fahrenheit  scale.     Example:  10°  C.^5 
18+32  =  50°  F. 


CHAPTER  V 

DESTRUCTION  OF  BACTERIA  BY  CHEMICALS 
AND  THEIR  PRACTICAL  USE 

IT  has  been  shown  how  bacteria  can  be  killed  by  heat, 
and  now  the  chemical  methods  of  destroying  infective 
material  will  be  discussed,  and  how  this  may  be  done 
practically.  Chemicals  either  in  solution  or  as  gas 
are  supposed  to  kill  bacteria  by  one  of  several  methods. 
The  whole  bacterial  body  may  be  destroyed  or  the 
protoplasm  may  be  entered  by  a  diffusion  of  the 
substance  through  the  cell  wall  with  consequent 
coagulation  or  solution.  It  is  said  also  that  the  rapid 
withdrawal  of  water  by  some  salts  may  be  fatal  to  the 
microorganism. 

There  is  some  confusion  as  to  the  terms  used  for 
chemical  bacteria-killing,  and  for  this  reason  it 
may  be  well  to  start  out  with  Park's  classification, 
(l)  Attenuation  is  when  the  pathogenic  or  vital  func- 
tions of  the  bacteria  are  temporarily  diminished.  (2) 
Antiseptic  action  is  when  the  bacteria  are  not  able  to 
multiply,  but  are  not  destroyed;  they  will  reproduce 
when  suitable  conditions  for  life  are  restored.  (3)  In- 
complete sterilization  or  disinfection  is  when  the  vege- 
tative forms  but  not  the  spores  are  destroyed.  (4) 
Sterilization  or  disinfection  is  when  both  vegetative 
and  spore  forms  are  destroyed;  this  implies  also  the 


SILVER  NITRATE  49 

destruction   of  any  products  of  bacteria  capable   of 
producing  disease. 

A  chemical  is  tested  for  its  antibacterial  properties 
in  several  ways,  chief  among  which  is  the  immersion 
of  some  of  the  pure  bacterial  growth  in  solutions  of 
various  strengths  of  the  chemicals. 

Some  of  the  individual  disinfectants  are: 

Bichloride  of  Mercury  (corrosive  sublimate). — This  is 
soluble  in  16  parts  of  cold  water.  One  part  in  100,000 
inhibits  most  bacteria.  In  twice  that  strength  many 
kinds  are  killed  in  a  few  minutes.  Spores  are  destroyed 
in  1  to  500  solution  in  water  within  one  hour.  In  order 
to  obtain  the  best  results  with  this  corrosive  sublimate 
it  is  necessary  to  have  an  acid  reaction,  so  that  most  of 
the  tablets  now  on  the  market  are  made  up  with  an 
acid  having  no  effect  upon  the  mercury  salt.  This  is 
particularly  true  when  the  material  to  be  disinfected 
is  pus,  blood,  feces,  or  the  like.  It  is  wise  to  use  a 
strength  of  1  to  500  for  one-half  an  hour  when  any 
such  organic  material  is  present.  The  disadvantages 
of  this  substance  are,  beside  that  mentioned  above, 
that  it  corrodes  metals,  and  is  rather  hard  on  the  skin. 
It  is  well  to  add  some  coloring  matter  to  the  solution 
for  the  purpose  of  identification,  since  this  is  a  rapidly 
acting,  corrosive,  deadly  poison.  Great  care  should  be 
used  in  keeping  the  tablets  and  solutions,  as  many 
accidents  have  occurred.  Being  odorless  it  attracts 
no  attention. 

Silver  Nitrate. — Park  says  that  this  salt  has  one- 
fourth   the  value  of  the  preceding  as  a  disinfectant, 
but   nearly   the   same   value   in   restraining  bacterial 
growth. 
4 


50      DESTRUCTION  OF  BACTERIA  BY  CHEMICALS 

Copper  Sulphate. — This  chemical  is  potent  against 
typhoid  in  water  in  the  presence  of  little  organic 
material  in  the  strength  of  1  to  400,000  in  twenty- 
four  hours. 

Sodium  Hydroxide  (caustic  soda). — This  substance  is 
very  destructive  to  fabric  and  to  the  skin,  but  kills, 
in  the  strength  of  1  to  100,  vegetative  bacteria  in  a 
few  minutes,  or  spores  are  destroyed  by  4  per  cent, 
solution  in  forty-five  minutes. 

Sodium  Carbonate. — This  chemical,  advantageous  for 
boiling  instruments,  kills  vegetative  forms  in  5  per 
cent,  solution  very  quickly,  or  spores  in  boiling  water 
in  about  five  minutes. 

"  Chloride  of  Dme"  (chlorinated  lime). — This  chemical 
is  also  known  as  bleaching  powder.  There  is  a  differ- 
ence of  opinion  as  to  its  composition.  Its  power  de- 
pends upon  the  liberation  of  free  chlorine  gas.  It  is 
destructive  to  fabrics.  It  quickly  degenerates  and  is 
therefore  to  be  used  fresh.  A  1  per  cent,  solution  will 
kill  all  non-spore-bearing  organisms  in  five  minutes, 
and  a  5  per  cent,  solution  destroys  spores  in  one  hour. 
Cakium  hydroxide,  made  by  adding  water  to  quick- 
lime, is  efficient  against  typhoid  bacilli  in  feces  when 
a  20  per  cent  solution  is  added  to  thoroughly  mixed 
feces  in  equal  parts  and  exposed  one  hour. 

Acids. — The  strong  mineral  acids  are  not  practical 
disinfectants,  but  nevertheless,  very  efficient.  Boric 
acid  kills  the  less  resistant  organisms  in  a  2  per  cent, 
solution,  but  only  after  some  hours'  exposure. 

Gaseous  Disinfectants. — There  are  only  three  of 
practical  value.  They  are  sulphur  dioxide,  oxygen 
from  hydrogen  dioxide  and  formaldehyde.  Chlorine 


FORMALDEHYDE  51 

is  not  included  here  because  it  is  seldom  used  in  its 
pure  state  since  it  is  highly  poisonous  and  destructive. 
It  is  eminently  efficient. 

Sulphur  Dioxide. — Sulphur  dioxide  is  used  for  hos- 
pitals, apartments,  and  ships.  It  is  more  efficient 
when  there  is  considerable  moisture  in  the  air.  When 
conditions  are  suitable  for  disinfection,  anthrax  bacilli 
in  the  vegetative  condition  are  destroyed  in  thirty 
minutes  when  there  is  1  volume  per  cent,  of  the  gas 
in  the  given  space.  "Four  pounds  of  sulphur  burned 
for  each  1000  cubic  feet  will  give  an  excess  of  gas/5 
Some  water  should  be  sprayed  in  the  room  or  an  open 
vessel  containing  water  should  be  there.  It  has  been 
suggested  that  the  sulphur  candles  of  commerce  be 
burned  resting  on  a  brick  in  a  bucket  of  water. 

Dioxide  of  Hydrogen. — A  2  per  cent,  solution  of  the 
pure  substance  will  kill  anthrax  spores  within  three 
hours.  In  20  per  cent,  solution  it  kills  vegetative 
bacteria,  pus  cocci  and  the  like  in  a  few  minutes.  Its 
activity  depends  upon  the  liberation  of  free  oxygen. 
It  should  be  kept  tightly  sealed,  since  it  easily  gives 
up  this  gas. 

Formaldehyde. — This  is  a  gas,  but  is  most  commonly 
seen  as  a  solution  ordinarily  known  under  its  trade 
name  formalin.  This  contains  from  35  to  40  per  cent, 
of  the  gas  and  also  some  wood  alcohol.  The  gas  has 
an  affinity  for  many  organic  substances,  among  them 
some  of  the  dyes,  but  fabric  is  not  affected.  Of  the 
metals,  iron  and  steel  are  attacked  after  long  exposure 
in  the  presence  of  moisture.  By  reason  of  its  affinity 
for  organic  substances  it  is  a  good  deodorizer  and 


52     DESTRUCTION  OF  BACTERIA  BY  CHEMICALS 

disinfectant  chiefly  because  it  forms  new  insoluble 
odorless  compounds. 

It  is  not  very  irritant  when  taken  into  stomach,  but 
vapors  cause  considerable  annoyance  in  the  eyes,  nose, 
and  mouth.  The  lower  animals  resist  it  considerably, 
but  insects  are  not  affected.  It  is  more  effective  in 
the  presence  of  moisture  and  when  the  temperature  is 
high,  up  to  120°  F.  If  these  conditions  cannot  be 
obtained  the  exposure  must  be  longer.  Two  and  one- 
half  per  cent,  by  volume  of  the  aqueous  solution  or 
1  per  cent,  by  volume  of  gas  are  sufficient  to  destroy 
fresh  virulent  cultures  of  the  common  non-spore-bearing 
bacteria  in  a  few  minutes. 

Carbolic  Acid  or  Phenol. — This  is  a  crystalline  solid 
which  softens  when  exposed  to  the  air.  It  is  soluble 
in  15  parts  of  water.  It  must  be  thoroughly  mixed  with 
material  to  be  disinfected.  It  is  not  destructive  to 
fabrics  or  colors.  It  acts  best  at  about  the  body 
temperature.  It  is  not  much  affected  by  the  presence 
of  organic  substances.  A  5  per  cent,  solution  kills 
spores  in  a  few  hours,  and  1  to  1000  inhibits  the  growth 
of  all  bacteria  and  may  be  considered  as  an  antiseptic; 
3  per  cent,  solutions  kill  the  pus  cocci  in  one  minute. 

Cresols. — These  are  thick  sticky  brown  fluids  related 
to  carbolic  acid.  They  make  a  milky  emulsion  with 
water.  The  best  known  ones  are  tricresol,  creolin, 
and  lysol.  The  two  latter  are  probably  the  best,  as 
they  mix  with  water  fairly  well.  All  these  substances 
in  5  per  cent,  emulsion  kill  the  ordinary  bacteria 
within  three  minutes  and  the  spore-formers  within  an 
hour. 


STOCK  SOLUTIONS  53 

Other  Disinfectants. — Ordinary  alcohol  kills  vegeta- 
tive forms  in  a  few  hours.  A  70  per  cent,  alcohol  is 
perhaps  the  most  potent.  It  has  lately  been  shown 
that  for  surface  disinfection  no  method  is  superior  to 
10  per  cent,  iodine  in  70  per  cent,  alcohol.  Some 
defenders  of  this  method  maintain  that  its  penetrating 
powers  exceed  any  other  known  practical  disinfectant. 
The  method,  while  undoubtedly  excellent,  must  remain 
for  a  while  sub  judice  before  one  can  accept  this 
statement.  Chloroform  kills  vegetative  bacteria  and 
restrains  spores,  even  in  small  qualities.  Ordinary 
soap  is  a  good  disinfectant,  particularly  by  its  solvent 
power  on  the  simple  organic  substances.  Its  effect  is 
increased  by  the  addition  of  common  washing  soda. 


PRACTICAL  APPLICATION  OF  DISINFECTION 

Stock  Solutions. — As  given  by  Park,  these  can  be 
made  as  follows:  6  ounces  of  carbolic  acid  in  1  gallon 
of  hot  water — this  is  about  a  5  per  cent,  solution.  It 
is  milky  at  first  and  must  be  stirred  thoroughly. 

Bichloride  solution :  60  grains  of  pulverized  bichlor- 
ide and  2  tablespoonfuls  of  common  salfc  to  1  gallon 
of  hot  water  =  1  to  1000.  Store  in  glass  or  earthen 
vessel.  Agate  will  answer.  It  is  well  to  color  the 
liquid  or  to  have  a  prominent  label  indicating  poison. 

Milk  of  lime:  1  quart  of  dry,  freshly  slaked  lime 
to  4  or  5  quarts  of  water.  Lime  is  slaked  by  pouring  a 
small  quantity  of  water  on  a  lump  of  quick  lime.  The 
lime  becomes  hot,  crumbles,  and  as  the  slaking  is 
completed  a  white  powder  results. 


54     DESTRUCTION  OF  BACTERIA  BY  CHEMICALS 

Formalin  solution:  1  part  of  formalin  to  10  of 
water  is  equivalent  to  5  per  cent,  of  carbolic  acid. 

Cleansing  of  Skin.  For  this  purpose  a  1  to  100 
carbolic  or  1  to  1000  bichloride  should  be  used,  allow- 
ing it  to  act  for  at  least  two  minutes.  Following  this 
there  should  be  scrubbing  with  soap  and  water  with 
a  soft  brush.  It  is  unwise  to  roughen  the  skin  with 
stiff  bristles.  The  newer  methods,  using  iodine-alcohol, 
require  only  simple  soap  and  water  washing  and  then 
a  few  applications  of  the  solutions  to  the  skin  to  be 
disinfected,  allowing  each  application  to  dry  before 
proceeding. 

Fabrics. — Soiled  fabrics  should  be  soaked  in  carbolic, 
formalin,  or  bichloride  in  this  order  of  preference  for 
at  least  two  hours.  Mattresses  should  be  exposed  to 
the  sun  or  removed  by  the  authorities  for  disinfection. 
After  soaking  infected  goods  in  these  solutions  they 
should  be  boiled  for  at  least  twenty  minutes,  preferably 
with  soap.  Materials  from  the  sick-room  should 
never  be  carried  to  other  parts  of  the  building  in  a 
dry  state. 

Utensils. — Utensils  should  be  soaked  in  the  solutions 
and  then  boiled. 

Urine,  Feces,  and  Sputum. — Urine,  feces,  and  sputum 
should  be  received  in  glass,  earthen,  or  agate  vessels 
already  containing  carbolic  acid  solution,  milk  of  lime 
or  formalin,  and  they  should  be  allowed  to  remain 
for  at  least  one  hour.  It  is  well  to  cover  the  vessel. 
In  the  absence  of  disinfectants,  discharges  should  be 
burned  or  boiled  for  one-half  hour.  The  solid  masses 
of  feces  should  be  broken  up  in  order  to  permit  the 
proper  penetration  of  solutions. 


DISINFECTION  OF  ROOMS  AND  HOUSES       55 

Tuberculous  Sputum. — Perhaps  nothing  is  so  impor- 
tant as  the  disinfection  of  tuberculous  sputum,  as  it  is 
the  chief  means  of  the  transmission  of  tuberculosis. 
It  should  be  received  preferably  in  a  pasteboard  cup 
within  a  metal  holder,  the  former  being  burned.  It 
may  be  caught  in  metal  or  agate  cups  containing  car- 
bolic or  milk  of  lime  solution.  If  caught  in  handker- 
chiefs they  should  be  burned.  The  hands  must  be 
washed  in  a  disinfectant  after  catching  sputum  in  a 
handkerchief. 

Fia.  20 


Sanitary  spit-cups 

Water-closets  and  Sinks. — They  should  not  receive 
infective  materials  until  these  shall  have  been  thor- 
oughly disinfected.  To  disinfect  sinks  and  water- 
closets,  chlorinated  lime,  cresols,  and  carbolic  acid  are 
the  best. 

Disinfection  of  Rooms  and  Houses. — The  disinfection 
of  rooms  and  their  contents,  while  not  necessarily  the 
nurse's  duty,  deserves  some  mention.  In  case  of 


56     DESTRUCTION  OF  BACTERIA  BY  CHEMICALS 

infectious  disease,  physical  cleaning  must  be  left  until 
after  chemical  disinfection  shall  have  been  done.  It  is 
then  carried  out  on  the  ordinary  plan  of  house-cleaning. 
The  practical  methods  of  house-disinfection  today  have 
narrowed  down  to  formaldehyde.  There  are  many 
forms  of  apparatus  and  several  methods  of  producing 
this  gas,  but  whatever  the  procedure,  certain  conditions 
must  be  observed.  The  temperature  of  air  in  the  room 
must  not  be  less  than  100°  F.,  and  there  should  be  a 
high  percentage  of  moisture.  The  most  common 
method  now  used  for  the  production  of  formaldehyde 
gas  is  the  mixture  of  1  pint  of  commercial  formalin 
and  10  ounces  of  small  crystals  of  potassium  perman- 
ganate in  an  open  vessel  for  each  1000  cubic  feet  of 
air  space.  These  are  usually  mixed  in  the  centre  of  the 
room  in  a  tall  metal  case  of  some  sort,  surrounded 
by  water  which  serves  the  purpose  of  catching  any 
of  the  mixture  which  bubbles  over  or  extinguishing 
fire  which  sometimes  occurs  spontaneously.  The 
cracks  of  doors  and  windows  are  always  sealed  by 
pasting  strips  of  paper  over  them.  This  saves  much 
of  the  vapor  for  disinfection  and  protects  inmates  of 
other  parts  of  the  house. 

Instruments. — Instruments,  including  syringes,  may 
be  boiled  for  five  minutes  in  a  1  per  cent,  solution  of 
washing  soda.  Knives,  however,  should  be  kept  in 
alcohol.  Gauze  should  be  sterilized  at  120°  C.  or 
248°  F.  and  15  pounds  pressure. 

Pasteurization. — This  consists  in  the  heating  of  a 
substance,  milk  usually,  to  a  temperature  which  kills 
the  non-spore-bearing  bacilli,  and  holding  there  for  a 
few  minutes.  It  is  then  cooled  as  rapidly  as  possible 


SUNLIGHT  57 

to  a  point  at  which  bacteria  do  not  usually  multiply, 
that  of  the  ice-chest.  This  does  not  sterilize  the  sub- 
stance, but  in  the  case  of  milk  actually  renders  it  more 
likely  to  spoil  afterward  if  not  properly  taken  care  of. 
Sunlight. — A  most  admirable  disinfectant  is  sunlight. 
Direct  sunlight  will  eventually  kill  all  bacteria,  and  it 
is  wise  to  expose  materials  from  the  sick-room,  whether 
from  an  infectious  case  or  not,  to  as  much  sunlight  as 
possible. 


CHAPTER  VI 

THE  RELATION  OF  BACTERIA  TO  DISEASE 
-IMMUNITY 

THE  difference  between  saprophytes  and  parasites 
has  already  been  emphasized,  and  incidently  it  has 
been  learned  that  the  latter  may  for  a  short  time  lead 
a  life  comparable  to  that  of  the  former.  The  organisms 
that  produce  disease,  pathogenic,  are  everywhere, 
particularly  in  the  crowded  life  of  cities.  Not  only  are 
they  on  the  objects  of  our  environment,  but  within 
the  entrances  to  the  body.  Sometimes  organisms  are 
found  in  the  mouth  and  nose  which  are  classed  as 
pathogenic.  Certain  organisms  are  present  invariably 
in  the  alimentary  canal  and  under  proper  circum- 
stances can  produce  disease.  It  is  often  difficult,  there- 
fore, to  determine  precisely  how  a  bacterium  enters 
the  body  and  produces  the  disease,  because  it  is  evident 
that  some  factors  other  than  the  simple  presence  of 
microorganisms  are  necessary  to  develop  what  is 
termed  sickness.  A  disease  might  be  fairly  well 
described  as  the  subjective  (experienced  by  the  patient) 
and  objective  (perceived  by  the  physician)  expression 
of  the  forces  exerted  by  the  bacteria  and  the  defense 
presented  by  the  body. 

•     These   two   forces   must    now    be    considered,  and 
following  the  natural  sequence,  bacteria  will  be  traced 


RELATION  OF  BACTERIA   TO  DISEASE        59 

in  their  usual  seats  upon  and  within  the  human  body, 
in  their  course  past  the  primary  defenses  and  their 
manner  of  awakening  the  secondary  or  peculiar 
immunity  resistances  which  the  human  system  pre- 
sents. Bacteria  gain  entrance  to  the  body  by 
introduction  through  an  abraded  surface  of  the  skin 
or  mucous  membranes.  The  delicacy  of  the  latter 
renders  infection  through  them  quite  easy.  They 
may  go  in  through  the  intestinal  tract  and  be  absorbed 
by  its  wall.  They  may  go  in  through  the  tonsils, 
larynx,  or  trachea.  In  exposure  to  cold  with  the 
congestion  and  sensitiveness  of  the  larynx  produced 
thereby,  we  have  an  opportunity  for  the  absorption  of 
bacteria.  Not  all  bacteria  can  enter  by  all  ways  and 
produce  disease.  The  pus  cocci,  if  swallowed,  are 
destroyed  by  the  gastric  juice,  while  typhoid  bacilli 
usually  pass  the  stomach  uninjured.  Typhoid  bacilli 
rubbed  into  the  skin  would  be  followed  by  no  disease, 
but  pus  cocci  so  applied  would  cause  boils.  Most  of 
the  secretions  and  excretions,  except,  of  course,  the 
feces,  may  be  said  to  be  mildly  inhibitive  to  bacterial 
growth.  The  defenses  of  the  body  to  a  local  introduc- 
tion of  bacteria  depend  upon  the  healthiness  of  the 
skin  and  mucous  membranes.  The  resistance  offered 
has  been  found  to  be  due  to  a  power  supplied  by  the 
blood  serum.  This  is  discussed  later.  Any  physical 
condition  such  as  a  burn  or  wound  reducing  the  healthy 
trim  of  the  body  renders  invasion  easier.  Injury  and 
intoxication  materially  favor  the  activity  of  bacteria 
either  previously  within  the  individual  or  introduced 
at  the  time.  Normal  bodily  resistance  is  impaired  by 


60     THE  RELATION  OF  BACTERIA   TO  DISEASE 

excessive  hunger  and  thirst,  by  exposure  to  cold  and 
wet,  or  by  prolonged  muscular  or  mental  strains. 

Conditions  resulting  after  the  entrance  of  bacteria 
into  the  body  may  be  defined  as  follows:  Infection  is 
best  considered  as  the  presence  of  disease-producing 
germs  and  the  evidence  of  their  effects.  Intoxication 
is  the  condition  due  to  the  poisons  elaborated  by 
bacteria.  Septicemia  or  bacteriemia  is  the  presence  of 
the  bacteria  and  their  products  circulating  in  the  blood, 
with  some  involvement  of  all  the  organs  in  the  body. 
Pyemia  is  similar  to  the  last  but  includes  the  pro- 
duction of  many  abscesses  throughout  the  body. 
Fever  may  be  described  as  a  disturbance  by  bacterial 
poisons  of  the  mechanism  in  the  brain  which  controls 
the  heat  of  the  body. 

Some  bacteria  merely  multiply  in  the  body  and 
exert  their  effect  simply  by  their  mechanical  presence 
without  any  peculiar  poison.  Others  have  the  power 
of  elaborating  poisons  that  are  specific  or  individual 
whose  effect  is  added  to  that  of  the  bacterial  bodies. 
The  latter  form  the  larger  percentage,  and  it  is  with 
them  we  shall  deal  chiefly.  The  ability  of  bacteria  to 
cause  disease  is  spoken  of  as  their  virulence.  Each  indi- 
vidual kind  of  bacterium  produces  only  one  form  of 
disease  and  always  that  one  form.  In  the  early 
history  of  pathological  bacteriology  Koch  elaborated 
certain  rules  or  postulates  by  which  the  relation  of 
bacteria  to  disease  is  determined.  They  are  essentially 
that  the  same  bacterium  should  always  be  found  in 
the  same  clinical  disease,  produce  this  disease  when 
injected  into  animals,  be  recovered  again  from  the 
animals  and  retain  its  biological  characters.  By  this 


THE  RELATION  OF  BACTERIA   TO  DISEASE     61 

means  the  peculiar  expression  of  bacterial  disease  has 
been  found,  and  thus  it  becomes  possible  to  separate 
those  diseases  which  are  wholly  due  to  the  bacteria 
themselves  and  those  principally  arising  from  the  bac- 
terial poisoning. 

Bacterial  Toxins. — Diphtheria  is  a  disease  wherein 
the  bacteria  reside  and  grow  on  a  free  surface  such  as 
the  mouth;  but  their  poisons  are  absorbed  and  carried 
in  the  blood  stream,  thus  producing  the  peculiar 
symptoms  of  the  disease.  If,  however,  this  toxin  is 
taken,  entirely  free  of  diphtheria  bacilli,  and  injected 
into  animals,  the  same  results  can  be  obtained  so 
far  as  the  symptoms  are  concerned.  This  is  likewise 
true  of  tetanus. 

For  the  development  of  typhoid  fever  and  septicemia 
it  is  necessary  that  the  bacteria  themselves  should 
circulate  in  the  blood  stream.  The  reason  for  this  is 
that  while  the  poisons  of  the  diphtheria  bacilli  are 
soluble  in  fluids  and  separable  from  the  germs,  the 
poisons  of  the  typhoid  bacillus,  for  instance,  remain 
within  the  body  of  the  germ  and  are  only  effective  when 
the  cell  dies  and  disintegrates.  The  former  poisons  are 
called  extracellular  toxins,  and  the  latter  intracellular 
toxins  or  endotoxins.  In  practice  the  word  toxin  unquali- 
fied means  extracellular  toxins,  while  intracellular 
poisons  are  specifically  called  endotoxins.  Some  bac- 
teria (cholera,  for  example)  develop  both  kinds. 

Bacterial  poisons,  it  might  be  said,  usually  express 
some  definite  predilection  for  special  organs  or  tissues. 
For  instance,  the  tetanus  toxins  attack  the  brain.  The 
streptococci  attack  red  blood  cells,  and  the  typhoid 
bacillus  settles  in  the  lymph  glands  of  the  small 
intestine. 


62      THE  RELATION  OF  BACTERIA   TO  DISEASE 

Incubation. — After  bacteria  have  gained  their  foot- 
hold there  is  a  certain  lapse  of  time  until  their  effects 
become  evident.  This  is  the  incubation  time.  Its 
length  depends  upon  the  number  of  organisms  enter- 
ing, their  virulence  and  the  resistance  of  the  body.  The 
local  gross  effects  of  bacterial  invasion  are  expressed  in 
inflammation,  which  is  greatest  in  those  which  act  by 
their  mechanical  presence  in  a  confined  locality,  usually 
aided  by  some  of  the  poisons  mentioned  above. 

Mixed  Infection. — Sometimes  there  is  more  than  one 
kind  of  bacterium  in  an  infection.  This  is  called  a 
mixed  infection  and  although  there  is  the  expression 
of  both  causes,  one  usually  predominates.  This 
usually  results  from  the  entrance  of  the  second  invader, 
owing  to  the  lowered  resistance  of  the  body  produced 
by  the  first  invader. 

Transmission  of  Disease.  -  -  The  transmission  of 
diseases'  from  one  individual  to  another  takes  place 
in  various  ways,  but  it  may  be  said  in  general  that 
the  means  of  transference  must  present  conditions 
favorable  for  the  retention  of  virulence  on  the  part 
of  the  bacteria.  Some  bacteria,  notably  gonococci  and 
influenza  bacilli,  die  very  quickly  when  dried  or 
exposed  to  direct  light.  On  the  other  hand,  tubercle 
bacilli  resist  drying  and  diffuse  light  for  several  days. 
Coughing  and  spitting  transfer  infective  organisms 
from  the  mouth  to  the  air,  and  persons  in  the  vicinity 
may  receive  them.  Clothes  soiled  with  discharges, 
both  urine  and  feces,  from  typhoid  patients,  contain 
the  bacilli  and  are  capable  of  carrying  the  disease. 
Scales  from  the  skin  in  the  acute  eruptive  diseases  of 
children  may  transmit  infection.  Milk  and  water 


IMMUNITY  63 

have  been  known  to  transmit  diphtheria,  typhoid, 
scarlatina,  and  other  conditions.  Flies  are  potent 
carriers  of  typhoid  by  soiling  their  feet  on  excreta  and 
then  alighting  on  food.  Other  insects  such  as  mos- 
quitoes transmit  disease.  It  may  be  laid  down  as  a  law 
that  with  the  exception  of  the  few  infectious  disorders 
only  carried  by  insects,  intimate  personal  contact  is 
the  most  prolific  source  of  the  spread  of  disease. 

Bacteria  are  directly  the  cause  of  ptomain  poisoning, 
although  the  ones  concerned  may  not  live  within  the 
body.  Ptomain  poisoning  is  a  violent  irritation  of  the 
gastro-intestinal  tract  by  certain  poisons  produced 
from  putrefaction  of  meat  and  fish  by  bacteria.  The 
foods  may  be  little  or  none  altered  by  these  poisonous 
substances  in  them.  They  are  in  small  quantity  in 
the  food,  but  are  easily  and  quickly  absorbed.  It  is 
possible  that  for  a  short  time  after  ingestion  of  the 
meat  the  formation  of  these  ptomains  may  continue. 
The  ptomains  are  toxins,  but  they  are  formed  by  alter- 
ing the  chemical  composition  of  the  meat  rather  than 
by  any  peculiar  products  of  the  bacteria  or  poisons 
within  their  bodies.  The  condition  is  not  transferable. 


IMMUNITY 

The  resistance  offered  to  the  entrance  of  micro- 
organisms into  the  body  has  already  been  referred  to, 
and  now  the  method  by  which  our  physiology  gets  rid 
of  the  effects  of  these  noxious  agents  must  be  con- 
sidered. It  is  a  well-known  fact  that  illness  does  not 
occur  every  time  pathogenic  bacteria  gain  a  foot- 
hold on  or  within  the  body.  Sometimes  a  small 


04     THE  RELATION  OF  BACTERIA   TO  DISEASE 

number  of  bacteria  overcome  the  primary  defenses 
and  yield  when  the  reserve  powers  have  been  brought 
into  play.  Again,  a  low  grade  of  virulence  may  be 
possessed  by  the  invaders,  and  although  many  enter, 
the  specific  disease  process  is  halted  by  the  economy. 
Moreover,  some  individuals  seem  to  be  poor  hosts 
for  certain  bacteria,  while  others  are  received  readily. 
The  general  resistance  of  the  body  to  disease  is  spoken 
of  as  immunity.  Immunity  as  the  term  is  usually 
used  means  that  an  individual  is  not  susceptible  to  a 
disease,  but  not  necessarily  that  he  would  not  be 
infected  under  any  severe  circumstances. 

Types  of  Immunity. — Immunity  is  classified  as  (1) 
natural,  or  racial  or  species  immunity,  and  (2)  acquired 
immunity,  which  latter  has  been  further  divided  into 
active  and  passive. 

Natural  immunity  is  the  condition  wherein  a  certain 
disease  does  not  occur  in  the  type  of  animal  under 
consideration,  as  for  example,  the  dog  does  not  take 
typhoid  fever  even  when  fed  a  pure  culture  of  the 
specific  germs.  There  is  also  a  relative  natural  im- 
munity. Cats  present  great  resistance  to  infection 
with  anthrax. 

Racial  immunity  is  shown  by  great  resistance  of  the 
negro  to  yellow  fever. 

There  is  also  individual  immunity  as  shown  by  the 
passing  of  a  person  through  a  virulent  epidemic  without 
the  slightest  sign  of  illness. 

Acquired  immunity  is  that  resistance  which  a 
person  obtains  by  passing  through  an  attack  of  disease. 
That  a  second  attack  of  measles  or  scarlatina  seldom 
occurs  is  well  known.  This  is  seen  also  in  typhoid 


IMMUNITY  65 

fever.  Such  an  acquired  immunity  is  called  active 
acquired  immunity  because  the  economy  has  had  to 
work  for  its  protection.  There  is  also  a  passive  acquired 
immunity,  by  which  is  meant  that  some  protective 
substances  from  another  individual  are  added  to  the 
natural  resistance  of  the  body.  This  passive  acquired 
immunity  is  very  well  shown  in  diphtheria  when  the 
serum  of  a  horse  which  has  been  rendered  resistant 
to  the  toxin  of  the  diphtheria  bacilli  is  introduced. 
This  horse  is  said  to  possess  active  artificial  immunity 
because  it  has  received  the  poisons  themselves  in  such 
a  manner  that  its  blood  has  been  able  to  develop  anti- 
or  against-poisons  or  antitoxins,  strong  enough  to 
neutralize  the  toxins  of  the  diphtheria  bacilli.  This 
blood  is  suitable  to  be  transferred  to  another  individual, 
and  in  the  body  of  the  latter  offsets  the  effects  of  the 
toxin  of  the  diphtheria  bacillus.  In  other  words,  the 
horse's  economy  has  worked  actively  against  the  poison, 
whereas  the  person  receiving  the  horse's  serum  has  not 
worked,  but  merely  received  a  neutralizing  substance 
from  the  horse's  serum;  it  has  been  passive.  This 
passive  immunity  is  also  seen  in  the  treatment  of 
tetanus  by  an  antiserum  (see  antitoxins)  and  lately 
Flexner  has  elaborated  a  method  by  which  the  poisons 
of  the  meningitis  coccus  are  neutralized,  here  again 
by  using  the  serum  of  horses  injected  with  this  coccus. 
Artificial  immunity  is  one  that  has  been  produced 
intentionally  by  the  physician.  It  may  be  correctly 
applied  to  any  form  except  the  natural  or  active 
acquired  immunities,  but  it  is  usually  reserved  for  the 
various  procedures  in  experimental  medicine  whereby 
antiserums  or  vaccines  are  manufactured. 
5 


66      THE  RELATION  OF  BACTERIA   TO  DISEASE 

Principles  of  Vaccine  Treatment. — To  return  for  a 
space  to  active  immunity,  it  is  well  to  consider  here  the 
basis  of  the  present-day  bacterin  treatment,  details  of 
which  will  be  taken  up  later.  The  ordinary  vaccination 
against  smallpox  depends  upon  the  fact  that  human 
smallpox  virus,  passed  through  a  calf  for  a  number  of 
times,  loses  its  power  to  produce  smallpox  in  man. 
It  does  retain  power  to  produce  a  sore,  and  this  sore 
contains  sufficient  of  the  poison  related  to  smallpox 
virus  to  stimulate  in  the  vaccinated  person  a  condition 
resistant  to  the  virus  which  would  cause  true  general 
smallpox.  The  great  Pasteur  found  that  if  he  heated 
anthrax  bacilli  and  injected  them  into  sheep  these 
animals  became  resistant  to  the  disease  anthrax.  Since 
the  time  of  Pasteur  the  management  of  the  process 
which  has  been  called  "active  immunization"  has 
been  learned.  To  accomplish  this  a  virus  must  be 
treated  as  was  the  virus  of  smallpox,  that  is,  it  must 
be  rendered  incapable  of  causing  general  disease,  but 
it  must  not  be  so  altered  that  it  has  no  relation  to 
its  original  form.  The  living  organisms  can  be  taken 
and  subjected  to  higher  or  lower  temperatures  to  those 
preferred  by  the  individual  species,  or  they  may  be 
injected  into  animals  until  they  will  merely  live  with- 
out producing  disease.  This  is  called  reducing  viru- 
lence. They  may  be  killed  by  heat  or  obtained  in  mass 
and  crushed  and  ground  into  a  pulp.  Again,  the  broth 
or  other  material  upon  which  they  grow  may  be  used 
after  removing  the  bacterial  bodies  by  filtering  them 
off  through  porcelain  filters.  Having  obtained  the  virus 
in  a  reduced  state  either  dead  or  as  active  principles, 
it  is  injected  beneath  the  skin  of  the  individuals 


IMMUNITY  67 

whom  it  is  desired  to  protect,  beginning  in  minute 
doses  and  increasing  the  quantity  as  the  condition 
permits.  By  this  means  the  resistance  of  the  animal 
or  person  to  this  particular  germ  is  increased,  and  the 
process  corresponds  to  that  of  the  production  of  anti- 
toxin in  horses,  that  is,  making  an  anti-poison,  or  as  it 
is  called,  an  antibody.  The  method  just  described 
is  usually  reserved  for  the  bacteria  which  produce 
intracellular  or  endo-toxins.  The  method  has  been 
used  in  treating  anthrax,  typhoid,  cholera,  etc. 

Anti-endotoxins. — These  bodies,  comparable  to  anti- 
toxins, are  developed  in  the  blood  serum  when  the 
system  harbors  bacteria  whose  pathogenic  power 
depends  upon  intracellular  poisons.  Many  kinds  of 
anti-endotoxins  or  antibodies  (a  term  embracing  anti- 
toxins also  but  more  commonly  used  as  here)  are 
formed.  The  important  ones  are  discussed  under  the 
Actions  of  Bacterial  Toxins  and  Their  Antibodies. 
Their  presence  is  sought  by  special  technique  in  order 
that  we  may  substantiate  and  control  the  principles 
outlined  in  the  preceding  paragraph. 

Antitoxins. — The  production  of  antitoxins  hinges  on 
this  subject.  Antitoxins  may  be  described  as  the 
substances  produced  in  the  blood  or  blood  serum 
of  animals  injected  with  the  poisons  elaborated  by 
bacteria,  but  soluble  and  separable  from  the  germ  cells. 
The  toxins  used  to  make  the  injections  into  animals 
are  obtained  by  growing  the  bacteria  in  broth  and 
then  filtering  off  their  bodies.  They  are  distinguished 
from  the  poisons  described  in  a  preceding  paragraph 
in  that  no  destruction  of  the  germs  is  necessary  to 
produce  these  separable  toxins,  whereas  in  the  case  of  the 


68     THE  RELATION  OF  BACTERIA   TO  DISEASE 

bacteria  when  used  themselves  for  active  immunization, 
the  germ-cell  disintegrates  before  the  poison  escapes. 

Recapitulation. — To  recapitulate  briefly,  active  ac- 
quired immunity  is  produced  by  injection  of  living 
bacterial  cells  when  incapable  of  producing  disease, 
or  by  their  endocellular  poisons  or  extracellular 
separable  toxins.  In  the  case  of  the  latter  it  is  possible 
to  take  from  the  blood  serum  of  the  immune  animals 
something  which  will  neutralize  the  toxins  introduced, 
in  other  words,  the  principle  involved  in  making  of 
diphtheria  and  tetanus  antitoxin.  The  former,  non- 
virulent  germs  or  their  poisons,  is  used  now  as  the 
basis  of  bacterin  treatment. 

Action  of  Bacterial  Poisons  and  their  Antibodies. — This 
matter  is  very  complicated  and  not  by  any  means 
perfectly  understood  by  the  most  profound  scientists. 
It  is,  moreover,  unnecessary  to  enlarge  upon  it  in  a 
work  of  this  kind,  and  tracing  the  methods  as  simply 
as  possible  is  sufficient. 

The  free  soluble  toxins  stimulate  the  production 
of  antitoxins  which  have  an  attraction  for  the  toxin, 
and  for  it  only.  Therefore,  when  any  free  toxin  and 
free  antitoxin  come  together  they  combine,  and  one 
neutralizes  the  other. 

In  the  case  of  the  reaction  of  bacterial  cells  or  their 
endotoxins  the  result  is  more  complicated.  Many 
substances  are  formed,  again  called  anti-,  or  in  general, 
antibodies.  Three  will  be  considered:  (1)  The  anti- 
bodies which  dissolve  bacterial  cells;  (2)  those  which 
clump  them;  and  (3)  those  which  encourage  the  white 
cells  of  the  blood  to  eat  them.  The  substances  exist 
in  minute  quantities  in  normal  blood. 


IMMUNITY  69 

1.  Bacteriolysins. — The    first    antibodies    cause    a 
dissolving  of   the  bacterial    cells.     These    antibodies 
are  called   bacteriolysins  (adj.,  bacteriolytic) .    There 
is  in  all  blood,  whether  normal  or  subjected  to  im- 
munizing procedures,  a  substance  called  complement 
which  makes  possible  these  combinations  of  antibody 
and  germ. 

2.  Agglutinins. — Agglutinins   are   substances   which 
cause  clumping  of  bacterial  cells,  but  do  not  dissolve 
them.    They  are  made  use  of  in  the  diagnosis  of  some 
acute  fevers,  notably  in  the  Widal  reaction  of  typhoid 
(see  Typhoid  Fever). 

3.  Opsonins. — These  are  substances  which  act  upon 
bacteria  and  prepare  them  for  consumption   by  the 
white  cells  of  the  blood  (leukocytes).    These  cells  are 
also  migrating  cells,  as  they  leave  the  blood  stream 
and  wander  over  the  body.     These  leukocytes  are  also 
called  phagocytes  (adj.,  phagocytic)  because  they  can 
consume  foreign  bodies.     Bacteria  are  such,  and  it  is 
the   task   of   these   phagocytes   to    remove   them.     It 
has  been  found  that  in  some  conditions  their  power  of 
consuming  bacteria  is  below  par,  and,  further,  that  if 
small  numbers  of  germs  incapable  of  producing  disease 
are    introduced,    the    power    of    these    cells    may    be 
increased.     The  bodies  producing  this  increased  eating 
or   phagocytosis    are   the    antibodies,    opsonins,    sup- 
posed not  to  act  upon  the  white   cells,   but   upon  the 
bacteria  and   make  them  more  suitable  as  food  for 
the  leukocytes.    These  phenomena  have  put  a  valuable 
method  of    treatment    in    the  physician's    hand.      In 
subacute    localized    disorders,    particularly,    but    also 
in    definitely    acute    and   chronic  troubles,    injections 


70      THE  RELATION  OF  BACTERIA   TO  DISEASE 

of  dead  cultures  of  the  bacteria,  responsible  for  the 
condition,  are  made  beneath  the  skin.  The  principles 
of  this  treatment  were  discussed  on  page  66.  The 
progress  of  treatment  is  followed  by  a  long  elaborate 
technique  of  permitting  the  leukocytes  of  the  blood 
of  the  patient,  and  as  a  control,  those  of  a  healthy 
person,  to  feed  upon  the  bacteria  in  question,  in  test- 
tubes  kept  at  body  heat.  If  the  number  of  germs 
consumed  by  the  patient's  leukocytes  rises  during  the 
course  of  the  treatment,  he  is  considered  as  benefiting 
from  the  injections.  His  general  constitutional  con- 
dition is  closely  watched  also.  It  is  now  attempted 
to  use  for  "vaccination"  a  culture  made  from  the 
patient's  disease. 

The  reader  must  not  picture  that  these  so-called 
antibodies  are  substances  that  can  be  handled.  They 
are  invisible  chemical  parts  of  the  serum  of  the  blood, 
and  only  perceptible  through  extremely  delicate  labor- 
atory procedures.  The  present  conception  of  their 
action  was  worked  out  by  Dr.  Ehrlich,  a  German 
physician,  chemist,  and  physicist.  His  theory,  broadly 
speaking,  assumes  a  group  of  substances  circulating 
in  the  blood  which  can  be  stimulated  to  meet  and 
destroy  invaders,  and  thereby  protect  the  body. 
Besides  the  three  methods  above  outlined,  in  which 
practical  therapeutic  use  has  been  made  of  the  known 
facts  in  the  study  of  immunity,  still  others  have  been 
devised  but  they  are  scarcely  yet  out  of  their  experi- 
mental stage. 


CHAPTER    VII 

PREPARATIONS  FOR  AND  PROCURING  OF 

SPECIMENS  FOR  BACTERIOLOGICAL 

EXAMINATION 

WHILE  it  may  not  be  the  duty  of  the  nurse  to 
obtain  all  specimens  for  bacteriological  purposes,  she 
is  often  requested  to  obtain  the  more  common  things, 
and  it  behooves  her  to  know  how  this  should  be 
done. 

The  nurse  is  very  commonly  expected  to  prepare 
the  patient  for  technique  used  by  the  physician  in 
procuring  specimens,  and  she  should  know  the  more 
important  parts  of  such  technique. 

Collection  of  Pus. — For  the  taking  of  cultures  of 
pus  from  abscesses  or  from  infected  surfaces  of  ulcers 
or  sinuses,  an  applicator  usually  of  wood,  wound 
with  cotton  and  sterilized  within  a  glass  test-tube,  is 
used.  The  nurse  most  commonly  sees  this  in  con- 
nection with  throat  cultures.  When  this  applicator  is 
passed  over  the  diseased  surface  some  of  the  bacteria 
present  adhere  to  the  cotton.  The  adhering  particles 
are  transferred  by  the  physician  to  some  suitable  food 
upon  which  the  germs  will  grow.  In  preparing  an 
exposed  infected  surface  for  culture-taking,  the  nurse 
need  have  ready  only  sterile  water  or  a  very  weak 
(1  per  cent.)  boric  acid  or  sterile  physiological  salt 
solution.  Anything  stronger  may  destroy  the  bacteria. 


72 


BACTERIOLOGICAL  EXAMINATION 


Collection  of   Sputum.  —  Sputum    to    be    examined 
for    the    tubercle    bacillus    should    be    received    in  a 


Showing  the  method  of  taking  a  culture  from  the  pharynx.     (Morrow.) 
FIG.  22 


Wide  mouthed  bottle  for  collecting  sputum. 

thoroughly  cleansed  and  dried  wide-mouthed  bottle. 
This  is  given  to  the  patient  that  he  may  expectorate 


COLLECTION  OF  FECES  73 

directly  into  it.  When  the  specimen  has  been  collected 
by  the  patient  the  bottle,  including  the  inside  of  the 
mouth,  should  be  wiped  off  with  a  cloth  moistened  with 
5  per  cent,  carbolic  acid  solution.  When  specimens 
of  sputum  are  intended  for  careful  bacteriological 
cultivation  with  the  idea  of  finding  out  what  the 
causative  bacteria  in  the  case  may  be,  the  procedure 
is  different.  In  this  case  the  bottle,  again  a  wide- 
mouthed  one,  must  be  plugged  with  raw  cotton  and 
sterilized,  preferably  by  dry  heat.  Someone  should 
supervise  the  collection  of  the  specimen  and  see  that 
the  patient  spits  a  representative  (instruction  from 
doctor)  sample  directly  into  the  bottle,  and  does  not 
let  it  touch  the  outside  of  the  neck.  The  part  of  the 
cotton  plug  which  extends  beyond  the  mouth  of  the 
bottle  should  be  held  by  someone  and  the  stopper  part 
not  allowed  to  touch  anything  while  out  of  the  bottle. 
After  the  plug  is  replaced,  the  outside  of  the  bottle  is 
cleansed  as  for  tuberculosis  sputum. 

Collection  of  Urine. — The  collection  of  urine  for 
bacteriological  purposes  must  be  done  by  catheteri- 
zation,  using  all  possible  surgical  precautions  as  to 
hands  and  instruments.  The  urine  must  be  allowed 
to  fall  from  the  end  of  the  catheter  directly  into  a 
bottle  or  test-tube  sterilized  with  a  raw  cotton  plug. 
This  is  best  held  by  an  assistant  during  catheterization, 
so  that  it  will  not  be  contaminated. 

Collection  of  Feces. — The  best  method  of  collecting 
feces  is  to  have  them  passed  directly  into  a  sterilized 
Mason  jar.  This,  however,  is  not  always  practicable, 
and  they  may  be  received  in  a  thoroughly  cleansed  bed- 
pan or  chamber,  and  transferred  afterward  to  the  Mason 


74 


BACTERIOLOGICAL  EXAMINATION 


jar  by  pouring  or  by  a  pair  of  forceps  sterilized  by 
passing  through  the  flame.  The  cleansing  of  the 
receptacle  should  be  done  by  soap  and  water,  alcohol, 
and  sterile  water. 

Collection  of  Blood  for  Widal  Test. — In  preparing  for 
a  Widal  blood  test  (see  Typhoid  Fever)  the  finger  or 
ear  lobe  is  cleansed  with  soap  and  water  and  alcohol. 
It  is  then  pricked  with  a  needle  and  the  blood  collected 
on  unglazed  paper,  glass  slides,  or  in  glass  tubes.  For 
direct  examination  of  the  blood,  the  procedure  with 
the  patient  is  the  same. 

FIG.  23 


Forms  of  hypodermic  syringe:    A,  Koch's   syringe;    B,  syringe  of  Strohschein; 
C,  Overlack's  form. 


Technique  of  Punctures. — Perhaps  the  most  important 
bacteriological  technique  with  which  the  nurse  has  an 
important  duty  is  the  puncturing  of  cavities  such  as 
drawing  fluid  from  a  chest  or  knee,  the  cerebrospinal 
fluid  from  the  spinal  canal,  or  the  taking  of  blood  from 
a  vein.  For  all  these  the  skin  over  the  site  of  operation 
is  cleansed  precisely  as  for  a  major  operation.  It  is 


TECHNIQUE  OF  PUNCTURES        75 

the  practice  of  the  author  for  vein  puncture,  in  making 
a  blood  culture,  to  have  the  arm  at  the  bend  of  the 
elbow  inside  (sometimes  the  leg  is  used)  scrubbed  with 
soap  and  water,  using  a  very  soft  brush,  washed  with 
sterile  water,  alcohol,  ether,  and  a  wet  dressing  of 
1  to  5000  bichloride  of  mercury  applied.  This  remains 
for  two  or  three  hours,  and  when  ready  to  do  the 
operation,  a  goodly  quantity  of  sterile  water,  or 
preferably,  salt  solution,  is  doused  or  sopped  on  the 
skin.  The  purpose  of  this  sterilization  of  the  skin 
for  a  long  time  by  the  wet  dressing  is  to  destroy 
the  bacteria  always  present  in  the  deeper  layers.  They 
are  chiefly  small  white  cocci  not  unlike  the  cocci  that 
cause  abscesses.  They  will  be  considered  later  under 
the  name  Staphylococcus  epidermidis  albus. 

There  is  little  to  be  done  by  the  nurse  aside  from 
preparation  and  general  assistance,  but  she  should 
know  what  is  being  done  and  why. 

Fluids  are  removed  from  the  pleural  cavity  or 
spinal  canal  and  elsewhere  because  in  these  locations 
bacteria  of  specific  kind  or  in  characteristic  conditions 
are  to  be  found.  For  instance,  in  spotted  fever  (cere- 
brospinal  meningitis)  the  causative  germs  are  found 
within  the  pus  cells  as  double,  biscuit-shaped  cocci, 
and  they  have  a  particular  staining  reaction  by  which 
they  are  recognized  (see  Chapter  VIII). 

The  blood  is  taken  from  the  veins  and  grown  in 
broth  alone  or  broth  stiffened  with  gelatin  or  agar- 
agar  in  order  to  find  out  if  living  bacteria  are  circu- 
lating in  the  blood  stream,  as  is  the  case  in  typhoid 
fever  and  septicemia. 

For  entering  these  cavities  or  veins  a  syringe,  prefer- 


76  BACTERIOLOGICAL  EXAMINATION 

ably  of  glass,  with  a  good-sized  needle,  larger  than  the 
medicinal  hypodermic  type,  is  used.  The  syringe  and 
needle  may  be  sterilized  by  boiling,  with  a  pinch  of 
soda,  for  ten  minutes  or  by  autoclave,  the  best  means 
provided  the  operation  be  done  immediately.  Metal 
parts  will  rust  if  the  syringe  and  needle  are  sterilized 
by  moist  heat  and  allowed  to  dry  out.  The  hot  air 
oven  is  not  suitable  for  sterilizing  in  this  case. 


CHAPTER    VIII 

THE   ACUTE   CHIEFLY    LOCALIZED    INFEC- 
TIONS  OF   PUS   NATURE— THE 
PATHOGENIC  COCCI 

So  far  the  general  conditions  under  which  bacteria 
live,  grow,  and  exert  their  peculiar  forces  have  been 
considered,  but  now  a  more  direct  study  will  be  under- 
taken of  individual  groups  and  single  species,  with  the 
object  of  learning  what  the  various  diseases  due  to 
microorganisms  are,  and  what  relations  the  germs 
bear  to  the  clinical  disease. 

Perhaps  the  most  frequent  condition  a  nurse  has 
to  meet  is  an  abscess  or  local  surgical  infection  with 
or  without  pus.  All  the  technique  of  hospital  work 
hinges  on  the  fact  that  organisms  capable  of  producing 
pus  are  ubiquitous,  and  the  protection  of  wounds  or 
of  patients  of  medical  cases  with  their  lowered  vital 
resistance,  is  imperative.  There  is  no  one  germ  that 
always  produces  local  infection  or  pus,  but  many 
bacteria  possess  this  power.  Moreover,  some  bacteria 
may  produce  a  simple  abscess  in  one  case  and  a  violent 
inflammation  of  the  heart  lining  in  another.  This 
depends  in  part  upon  the  virulence  of  the  germ  and 
also  upon  its  mode  of  entry.  If  pus  cocci  fall  upon  a 
simple  cut  in  the  skin  of  an  otherwise  healthy  person, 
a  red,  dropsical  swelling,  or  an  abscess  may  result. 
Again,  if  they  fall  upon  a  wound  made  for  an  abdomi- 


78     LOCALIZED  INFECTIONS  OF  PUS  NATURE 

nal  operation,  they  may  penetrate  to  the  interior 
and  cause  a  peritonitis.  Still,  again,  pus  germs  may 
make  their  entrance  in  the  ways  first  cited,  but  cause 
no  trouble  at  the  site  of  entrance,  being  carried  hence 
by  the  blood  stream  to  cause  trouble  at  other  places. 
Any  reaction  set  up  by  bacteria  is  called  inflammation, 
and  in  no  other  conditions  is  this  so  well  illustrated  as 
in  the  effects  of  "pus  cocci." 

Inflammation. — Inflammation  is  the  reaction  on  the 
part  of  the  body  to  the  presence  of  bacteria  themselves  or 
to  their  products.  It  is  expressed  by  swelling,  increased 
heat,  redness,  pain,  and  some  loss  of  function.  It  is 
not  worth  while  to  go  deeply  into  what  may  be  seen 
under  the  microscope  in  inflammation,  but  to  explain 
the  physical  expressions  of  inflammation  just  given 
a  few  lines  seems  advisable.  The  swelling,  heat,  and 
redness  are  due  to  an  increase  of  the  blood  in  the 
affected  part,  called  forth  by  forces  exerted  by  the 
bacteria.  These  are  protective  phenomena  whereby  the 
body  sends  an  excess  of  its  most  potent  protective  tissue, 
the  blood,  to  stop  the  onslaught  of  microorganisms. 
The  forces  exerted  by  the  invaders  attract  the  white 
cells  of  the  blood,  which  collect  about  the  outsiders  and 
try  to  destroy  them.  The  pain  is  due  to  the  irritation 
of  the  fine  nerves  of  the  part,  and  loss  of  function  can 
be  explained  by  a  combination  of  all  the  other  features 
of  inflammation.  The  further  course  of  this  reaction 
depends  upon  which  force  is  the  stronger,  the  body 
defense  or  the  bacterial  attack.  If  the  former  exceeds 
the  latter  the  part  assumes  its  normal  character  after 
a  brief  time.  As  the  infecting  forces  become  greater 
in  relation  to  the  defense,  just  so  there  are  greater 


LOCALIZED  INFECTIONS  OF  PUS  NATURE     79 

effects  in  the  production  of  infection.     In  increasing 
severity  there  are  the  following  grades: 


FIG.  24 


Secondary  infection  of  a  glomerulus  of  kidney  by  the  Staphylococcus  aureus, 
in  a  case  of  ulcerative  endocarditis.  The  cocci  (stained  doubly)  are  seen 
plugging  the  capillaries  and  also  lying  free.  X  300.  (Muir  and  Ritchie.) 


Abscess. — A  local  collection  of  pus  in  which  the 
resistance  put  up  by  the  tissue  prevents  the  inflamma- 
tion from  going  on  to  the  next  grade,  or  diffuse,  not 
limited,  spreading  cellulitis  or  phlegmon,  or  to  multiple 
abscesses.  The  next  grade  of  severity  would  be 
septicemia  or  pyemia,  defined  before.  They  arise 
chiefly  when  the  active  inflammation  enters  and 
involves  the  bloodvessels.  The  softening  of  tissue 


SO     LOCALIZED  INFECTIONS  OF  PUS  NATURE 

into  pus  is  called  suppuration,  which  may  be  defined 
as  the  destruction  of  tissues  and  cells  by  the  products 
of  bacteria.  Pus  under  the  microscope  is  composed  of 
white  blood  cells,  particularly  the  so-called  polynuclear 
leukocytes,  microorganisms,  and  partly  or  wholly 
destroyed  tissue.  There  is  also  some  granular 
fluid. 

While  the  term  pus  is  applied  to  all  the  degenerated 
products  of  inflammation,  there  is  a  special  word  when 
the  material  collects  on  a  surface.  This  is  usually  desig- 
nated as  an  exudate.  For  example,  the  false  membrane 
of  diphtheria  is  called  an  exudate  as  is  also  the  fluid 
containing  shreds  within  the  pleural  or  abdominal 
cavities,  or  in  the  lungs  in  pneumonia. 

PUS-PRODUCING   MICROORGANISMS 

It  has  been  stated  that  there  is  no  particular  germ 
alway  responsible  for  pus,  but  there  is  a  small  group 
of  the  round  bacteria  most  commonly  present.  They 
are  called  micrococci  or  staphylococci,  and  strepto- 
cocci. Certain  members  of  the  group  of  cocci  may  also 
do  other  things  than  produce  simple  pus  or  abscesses. 
These  will  be  considered  at  the  end  of  this  chapter. 
Bacteria  other  than  cocci  which  can  produce  pus  are 
the  colon  bacillus,  pyocyaneus  bacillus,  typhoid  bacillus, 
pseudodiphtheria  bacillus. 

Staphylococcus  Pyogenes  Aureus. — Of  the  micrococci 
there  is  one  particular  species  of  importance  which 
by  some  bacteriologists  has  been  divided  into  two  on 
account  of  its  ability  to  produce  color  in  laboratory 
cultures  and  because  the  one  having  a  golden  yellow 


PLATE  II 


Cultures  of  Bacteria.     (Besson.) 

The  jellies  upon  w^ieh  the  pure  cultures  are  grown,  are 
hardened  in  test-tubes  in  a  slanting  position.  The  bacteria 
are  then  spread  along  the  oblique  surfaces  and  grow  in  bands 
or  streaks  as  shown  here. 


PUS-PRODUCING  MICROORGANISMS  81 

pigment  is  somewhat  more  frequently  found  in  pus. 
This  color-producing  organism  is  called  the  Staphylo- 
coccus  pyogenes  aureus  (the  golden  pus-producing 
coccus).  See  Plate  II  for  an  idea  of  growth  and  color. 
It  is  about  2TTRTO  of  an  inch  across  and  appears  under 
the  microscope  in  single  individuals,  pairs,  and  more  fre- 
quently, in  grape-like  groups.  It  stains  fairly  well  with 
most  dyes  used.  It  does  not  form  spores  and  does  not 
move  from  place  to  place  by  its  own  power.  It  grows 

FIG.  25 


Staphylococcus.     X  1100  diameters.     (Park.) 

best  about  85°  F.  It  is  killed  about  56°  C.  or  130°  F. 
at  ten  minutes  in  the  moist  condition,  but  when  com- 
pletely dry  it  may  require  boiling  to  kill.  When  dried 
on  cloth  or  paper  it  may  live  three  months.  This 
organism  grows  well  on  ordinary  laboratory  foodstuffs, 
and  produces,  particularly  in  the  presence  of  diffuse 
light  and  oxygen,  a  golden  yellow  color.  This  coccus 
has  the  property  of  coagulating  milk  and  liquefying 
gelatine  by  the  ferments  it  produces.  It  is  killed  by 
corrosive  sublimate,  1  to  1000,  in  ten  minutes  in 
6 


82     LOCALIZED  INFECTIONS  OF  PUS  NATURE 

watery  solution.  In  pus  a  considerably  longer  time  is 
required.  1  to  20  carbolic  kills  in  one  minute;  1  to 
500  in  about  one-half  hour.  The  pus  in  which  the 
staphylococcus  lives  supplies  a  protective  envelope, 
and  should  be  well  mixed  and  diluted  with  the  germi- 
cide. 

This  organism  is  very  virulent  for  the  smaller  animals, 
which  may  be  affected  even  by  rubbing  on,  or  injection 
under,  the  skin.  It  will  then  produce  a  local  abscess 
or  septicemia.  It  may  produce  acute  inflammation 
of  the  interior  of  the  heart  or  bone  disease. 

Staphylococcus  Pyogenes  Albus. — The  Staphylococcus 
pyogenes  albus  is  precisely  like  the  foregoing  except 
that  it  does  not  produce  the  golden  yellow  pigment, 
but  grows  in  a  porcelain-white  manner.  There  is  an 
organism  on  the  skin  to  which  we  give  the  same 
name,  but  add  the  word  "epidermidis."  It  is  con- 
stantly present  on  the  surface,  in  the  epidermis  and  in 
the  glands  of  the  skin.  Since  its  pus-forming  ability 
is  so  feeble,  "pyogenes"  may  be  omitted  and  the 
name  Staphylococcus  epidermidis  albus  given.  It  does 
not  produce  disease,  but  is  of  constant  annoyance  in 
making  blood  cultures.  Another  staphylococcus  pro- 
duces a  lemon-yellow  color. 

Opsonic  Index. — The  use  of  killed  bacteria  to  produce 
an  increased  resistance  against  an  existing  infection 
has  already  been  discussed.  This  method  of  treat- 
ment is  particularly  suitable  for  infections  with  these 
staphylococci.  The  procedure  is  about  as  follows: 
Cultures  are  made  from  the  diseased  part,  grown  in 
large  quantities  on  laboratory  media,  washed  off, 
suspended  in  physiological  salt  solution  and  heated  to 


PUS-PRODUCING  MICROORGANISMS          83 

a  temperature  which  will  kill  their  disease-producing 
properties  and  stop  their  multiplication,  but  will  not 
alter  their  peculiar  chemical  composition.  The  number 
of  bacteria  are  then  counted  by  a  special  technique  and 
hypodermic  injections  are  made  of  definite  numbers. 
The  size  of  dose  and  rate  of  increase  of  number  injected 
are  controlled  by  what  is  called  the  opsonic  index.  The 
opsonins,  as  will  be  remembered,  are  substances  in  the 
blood  which  make  the  bacteria  suitable  for  ingestion  by 
the  white  cells  of  the  blood  or  phagocytes.  The  opsonic 
index  is  the  relation  of  the  ability  of  the  patient's 
white  cells  to  ingest  bacteria  as  compared  with  a 
normal  person's  white  cells.  This  latter  is  considered  1. 
If  a  person  is  infected  with  the  pus  cocci  it  means 
that  his  opsonic  index  is  below  1,  and  we  try  to  increase 
it  up  to  or  beyond  1. 

Vaccine  Treatment. — The  theory  and  practice  of  this 
so-called  "vaccine  treatment"  or  treatment  with  killed 
bacteria  are  beset  with  many  difficulties,  and  must 
be  carried  out  by  specialists.  The  dead  cultures  are 
called  vaccines  or  bacterins.  Today  bacterins  made 
from  the  patients'  infecting  organism  are  chiefly  used, 
but  chemical  houses  are  putting  on  the  market  what 
are  called  stock  bacterins.  The  most  suitable  disease 
for  treatment  of  this  kind  is  furunculosis  (boils). 

Streptococcus  Pyogenes. — The  cocci  which  grow  in 
chains,  streptococci,  must  now  be  considered.  There 
are  many  varieties,  but  the  Streptococcus  pyogenes 
(the  pus-producing  streptococcus)  is  the  only  one 
that  need  be  considered.  This  organism  gives  rise 
chiefly  to  the  spreading  inflammation  such  as  ery- 
sipelas, cellulitis,  and  septicemia.  It  may  cause  a 


84     LOCALIZED  INFECTIONS  OF  PUS  NATURE 

localized  abscess.  It  is  a  rapidly  growing  organism 
when  conditions  are  suitable,  and  is  the  commonest 
cause  of  puerperal  infection.  It  frequently  attacks 
the  blood  and  causes  a  solution  of  the  red  cells.  It  is 
not  so  widespread  in  its  distribution  as  the  foregoing 
coccus,  but  is  greatly  feared  in  surgical  wards.  Strepto- 
coccus peritonitis  is  usually  fatal.  It  is  commonly 
present  in  the  mouth,  and  may  produce  tonsillitis. 
Disinfection  of  materials  from  streptococcic  infections 
should  be  done  by  carbolic,  bichloride,  or  hydrogen 
peroxide.  Great  care  is  necessary  in  the  handling  of 
dressings,  clothing,  and  utensils  from  patients  with 
streptococcus  infections,  because,  despite  the  low 
resistance  of  the  organism,  transmissions  take  place 
quite  easily.  When  the  particular  family  of  germs 
happens  to  be  very  virulent,  a  single  coccus  may 
transmit  an  infection. 

FIG.  26 
if"      ,-r      ..-"x 


Streptococcus  pyogenes.     (Abbott.) 

In  diagnosticating  streptococcic  infections  it  is 
necessary  to  make  smears  on  glass  slides  and  cultures 
in  appropriate  media.  The  germs  are  found  to  be  very 
small  single  cocci  varying  from  -simFiF  to  2TT07  of  an 
inch,  dividing  only  in  one  plane  and  therefore  growing 
in  chains.  They  are  unable  to  move  of  themselves, 


PUS-PRODUCING  MICROORGANISMS  85 

stain  well  by  most  methods,  multiply  best  at  37°  C. 
(98°  F.),  but  also  at  lower  temperatures,  and  grow  as 
very  delicate  gray  colonies.  They  have  no  effect  upon 
milk  or  gelatine.  On  media  containing  blood  they 
have  the  property  of  dissolving  the  red  coloring 
matter. 

They  are  killed  in  ten  minutes  when  exposed  to 
52°  C.  (126°  F.).  When  dried  in  blood  or  pus  they 
may  live  for  a  considerable  time  at  room  temperature, 
but  die  quickly  at  body  heat  unless  their  food  is 
repeatedly  renewed.  They  are  killed  by  corrosive 
sublimate,  1  to  1000;  carbolic  acid,  1  to  100;  and 
hydrogen  peroxide,  1  to  100,  in  ten  minutes  if  exposed 
in  water.  Pus  supplies  a  protective  envelope,  and  the 
germicide  must  be  allowed  to  act  longer.  Streptococci 
are  very  virulent  for  most  lower  animals  and  the  same 
lesions  may  be  produced  by  artificial  injection  as  arise 
spontaneously  in  man.  Streptococci  produce  a  slight 
amount  of  extracellular  poison,  but  more  arises  from 
the  disintegration  of  the  bacterial  cells.  Attempts  at 
producing  some  serum  to  neutralize  either  of  these 
toxins  have  met  with  little  success.  The  vaccine 
treatment  is  likewise  not  successful. 

To  diagnosticate  infections  by  the  staphylococcus 
or  streptococcus  we  are  obliged  to  make  our  technique 
suit  the  individual  case.  If  an  abscess  exist  it  is 
sufficient  to  collect  the  pus.  If  a  cellulitis  or  bone 
disease  is  to  be  examined,  it  is  necessary  to  go  deeply 
into  the  tissue  and  select  the  bloody  material  near 
the  healthier  tissue.  In  septicemia  or  heart  disease, 
a  blood  culture  is  made.  Both  organisms  grow  with 
ease  upon  ordinary  culture  media. 


86     LOCALIZED  INFECTIONS  OF  PUS  NATURE 

MICROCOCCUS  GONORRHOEA 

Gonorrhea  is  an  acute  inflammatory  and  pus-forming 
disease  with  its  chief  manifestations  in  the  mucous 
membrane  of  the  urethra.  It  is  caused  by  the  Micro- 
coccus  gonorrhoeas  or  gonococcus,  which  enters  the 
mucous  membrane  directly  wherever  there  is  a  slight 
chiefly  invisible  abrasion.  This  disease  is  one  of  the 
venereal  affections,  and  is  probably  one  of  the  most 
prevalent  of  all  diseases.  In  the  male  its  acute  stage 
lasts  for  three  to  six  weeks,  while  in  the  female  it  may 
be  transient  or  pursue  a  very  long  course.  In  both 
sexes  it  tends  to  infect  the  other  genital  organs,  and  is 
probably  the  chief  cause  of  salpingitis  and  oophoritis. 
The  causative  organisms  penetrates  to  the  deep  parts 
of  the  mucous  membrane  of  the  external  urinary 
channel,  and  there  rest  for  long  periods  apparently 
undestroyed  by  the  protective  forces  of  the  body,  and 
without  setting  up  any  change  by  which  their  presence 
can  be  detected.  It  may  be  stimulated  to  renewed 
activity  by  a  congestion  of  the  part  by  any  means. 
This  peculiarity  of  hiding  is  the  reason  for  the  fact 
that  a  person  once  affected  by  this  disease  remains 
infective  for  others  for  a  very  long  time.  The  bacteria 
resides  in  the  Bartholin's  glands  of  the  female  or  the 
posterior  urethra,  Cowper's  and  prostatic  glands  of 
the  male.  At  present  there  is  no  perfectly  reliable 
method  by  which  to  ascertain  the  freedom  from  gono- 
cocci  of  a  person  once  affected.  Late  results  of  this 
disease  are  urethral  stricture,  chronic  inflammation 
of  any  other  genitals,  such  as  salpingoophoritis,  requir- 
ing operative  removal  of  the  affected  parts.  Either 


MICROCOCCUS  GONORRHCEM  87 

during  its  acute  or  chronic  stage,  the  latter  more 
commonly,  the  gonococci  may  enter  the  blood  stream 
and  affect  tissues  other  than  the  genital,  for  which  it 
has  a  predilection,  the  serous  surfaces,  joints,  heart 
lining,  or  meninges.  These  conditions  arising  after 
such  spreading  are  very  difficult  to  treat,  and  not 
infrequently  leave  a  permanent  defect. 

The  inflammations  of  the  eyes,  notably  the  con- 
junctiva, produced  by  the  gonococcus  are  very  com- 
mon, and  one  authority  says  that  half  the  world's 
blindness  is  due  to  it.  This  complication  is  due  to 
carrying  of  germs  from  the  seat  of  primary  disease,  on 
the  fingers,  handkerchiefs,  and  the  like,  to  the  eye. 
The  result  is  a  frightful  acute,  pussy  conjunctivitis, 
running  a  long  acute  course  and  leaving  opacities  of 
the  cornea  or  adhesions  of  the  iris  in  many  cases. 
Destruction  of  the  eye  may  result.  Not  only  does 
this  disease  affect  those  with  gonorrhea,  but  it  may 
be  transferred  to  others  by  objects  soiled  with  pus. 
The  commonest  transmission  of  gonorrheal  ophthalmia, 
as  it  is  called,  is  to  the  newborn.  This  is  ophthalmia 
neonatorum.  It  is  a  common  practice  of  obstetricians, 
especially  in  hospitals,  to  instil  a  few  drops  of  a  weak 
nitrate  of  silver  solution  into  the  eyes  of  newborns, 
whether  there  is  or  is  not  a  history  of  gonorrhea  in 
the  mother. 

A  more  serious  and  baffling  phase  of  gonorrhea  is 
seen  in  the  vulvovaginitis  of  little  girls,  which  fre- 
quently sweeps  like  wildfire  through  a  hospital  ward, 
despite  all  attempts  to  stay  its  progress.  It  also 
appears  in  any  institution  where  children  are  in  close 
contact,  schools,  for  example.  It  is  supposed  to  be 


88     LOCALIZED  INFECTIONS  OF  PUS  NATURE 

transmitted  by  water-closet  seats  and  directly  from 
child  to  child.  It  may  be  spread  by  bedclothes,  towels, 
clothing,  basins,  bed-pans,  and  in  other  ways.  Children 
have  been  known  to  contract  the  affection  by  sleeping 
with  some  one  with  gonorrhea.  Efforts  to  eradicate 
this  vulvovaginitis  should  be  directed  toward  removing 
the  source.  This  is  sometimes  impossible,  since  it 
cannot  always  be  found.  It  is  much  better  to  insti- 
tute a  strict  quarantine  of  every  little  girl  admitted  to 
a  ward  by  using  separate  bed  and  body  clothing  and 
utensils.  She  should  be  examined  by  the  house  physician 
upon  admission,  and  if  necessary,  proper  bacteriologi- 
cal examinations  made.  If  affected,  such  objects 
that  are  used  on  her  as  can  be  burned  should  be  so 
disposed  of.  Others  should  be  soaked  in  carbolic 
acid  solution  for  at  least  twenty-four  hours.  It  is 
the  practice  in  many  places  to  place  on  all  female 
children  a  T-binder,  which  is  burned  upon  removal. 
Patients  must  not  be  allowed  to  go  to  the  water-closet, 
but  a  bed-pan  used,  to  be  later  disinfected  by  appro- 
priate solutions.  Flaming  objects  such  as  a  bed-pan 
is  an  excellent  method  of  disinfection.  The  curious 
part  about  the  transmission  of  vulvovaginitis  is  that 
its  causative  agent,  presumably  always  the  gonococcus, 
is  either  in  a  highly  resistant  state,  or  it  is  protected 
in  some  manner,  since  agencies,  such  as  drying,  that 
will  kill  the  bacterium  under  ordinary  conditions 
seem  to  have  little  or  no  effect  upon  it. 

The  gonococcus  was  first  described  by  Neisser  in 
1879.  It  is  classified,  and  correctly,  among  the  round 
organisms  or  cocci,  although  it  is  usually  seen  in  pairs 
like  two  kidney  beans  with  their  concave  sides  together. 


MICROCOCCUS  GONORRH(E£  89 

They  are  also  said  to  be  of  biscuit  shape.  Each  bean  is 
about  -g"o1ro  o  °f  an  mcn  wide  and  yg-Jinr  of  an  inch  long. 
In  pus  or  culture  they  are  of  this  figure,  but  in  the 
former  they  are  characteristically  lying  within  the 
pus  cells  between  the  wall  and  the  nucleus,  but  not 
within  the  latter.  Free  pairs  are  also  seen,  but  it  is 
unwise  to  name  them  when  not  in  the  cells,  because 
other  cocci  may  resemble  them.  There  is  a  resem- 
blance between  these  organisms  and  those  of  meningitis 
(p.  92),  but  the  clinical  differentiation  is  not  difficult, 
since  the  diseases  are  easily  separated. 


FIG.  27 


t,  "* 

-.**    ^     , 


Pus  of  gonorrhea,  showing  diplococci  in  the  bodies  of  the  pus  cells. 
(Abbott.) 


The  gonococcus  does  not  stain  by  Gram's  method, 
a  quite  important  criterion  for  the  bacteriologist.  It 
is  cultivated  with  difficulty.  For  purposes  of  growing 
it  in  the  laboratory  a  broth  or  jelly  must  be  used  to 
which  has  been  added  some  blood  or  blood  serum  or 
fluid  from  a  hydrocele  or  the  peritoneum.  It  grows 
best  in  the  presence  of  free  oxygen,  a  curious  fact, 


90     LOCALIZED  INFECTIONS  OF  PUS  NATURE 

since  it  will  live  for  long  periods  in  places  where  there 
is  no  free  oxygen.  It  grows  best  at  98°  F.  (37.5°  C.) 
but  dies  out  very  rapidly.  In  the  ice-chest  it  may  live 
somewhat  longer. 

Direct  sunlight  kills  the  gonococcus  almost  at  once. 
105°  F.  (41°  G.)  will  kill  the  organism  in  a  few  minutes. 
Almost  any  good  disinfectant  will  kill  it  in  five  minutes 
if  directly  applied  to  the  bare  germ.  "If  completely 
dried,  however,  and  protected  from  light,  it  may  live 
on  sheets  and  clothing,  from  eighteen  to  twenty-four 
hours." 

This  bacterium  produces  an  intracellular  or  endo- 
toxin,  which  is  as  potent  when  injected  into  animals  as 
a  devitalized  mass  as  the  living  form  itself,  although 
the  gonococcus  has  very  little  effect  upon  laboratory 
experimental  animals.  Some  observers  have  been 
able,  by  injecting  goats  with  coccus  poison  or  the 
germs  themselves,  to  produce  an  antiserum  against 
the  gonococcus,  and  therewith  treat  human  cases  with 
some  success. 

The  bacteriological  diagnosis  is  easily  made  by 
spreading  some  of  the  pus  upon  glass  slides,  staining 
appropriately,  and  examining  under  the  microscope. 
In  the  chronic  gonococcus  infection  the  discovery  of 
the  germ  is  extremely  difficult. 


MICROCOCCUS  INTRACELLULARIS  MENINGITIDIS 

Meningitis,  or  inflammation  of  the  membranes 
covering  the  brain  and  spinal  cord,  may  be  caused  by 
several  bacteria,  such  as  streptococci,  pneumococci, 


MICROCOCCUS  MENINGITIDIS  91 

and  influenza  bacilli,  but  we  shall  deal  chiefly  with 
epidemic  cerebrospinal  meningitis  or  spotted  fever. 
(The  latter  is  a  common  term  which  should  be  dis- 
carded for  meningitis,  and  confined  to  typhus  or 
jail  fever.)  Epidemic  cerebrospinal  meningitis  is  an 
acute  primary  inflammation  due  to  a  coccus  called 
the  Micrococcus  or  Diplococcus  intracellularis  menin- 
gitidis  of  Weichselbaum  or  the  meningitis  coccus  or 
meningococcus.  The  organism  probably  enters  the 
spaces  between  the  nervous  organs  and  their  bony 
casement  by  way  of  the  nose,  whence  it  penetrates  the 
sieve-like  plate  at  the  top  into  the  space  beneath  the 
brain,  and  proceeds  by  extension. 

The  other  forms  of  meningitis,  the  pneumococcal  for 
instance,  gains  entrance  by  way  of  the  blood  or  lymph, 
directly  through  the  skull-base  or  by  an  extension  from 
the  middle  ear,  where  suppuration  may  burrow  through 
the  bone. 

The  meningitis  coccus  may  be  found  in  the  nose 
and  throat  of  patients,  and  indeed  also  in  the  nose  and 
throat  of  those  attending  them. 

The  affection  produces  a  thick,  stringy,  purulent 
exudate  in  the  spaces  between  the  nervous  system 
and  their  coverings,  the  meninges,  called  the  arachnoid 
space.  This  exudate  covers  the  brain  and  cord,  and 
fluid  accompanying  it  distends  the  various  cavities  of 
the  spinal  column  and  interior  of  the  brain.  The  dis- 
ease has  a  high  mortality.  It  affects  chiefly  the  young. 
Its  results  or  sequelae  consist  in  blindness,  deafness, 
and  paralyses  of  various  kinds.  Mentality  may  be 
affected. 

In    taking    care    of    meningitis    patients    the    chief 


92     LOCALIZED  INFECTIONS  OF  PUS  NATURE 

concern  is  with  discharges  from  the  nose  and  mouth. 
These  cavities  should  be  cleansed  with  a  mild  anti- 
septic, say  boric  acid,  and  the  cotton  or  what  not  used 
should  be  burned  or  soaked  in  carbolic  acid  solution. 

FIG.  28 


V 

«;. 


'* 


t 


:»„ 


Meningococcus  in  spinal  fluid.     (Hiss  and  Zinsser.) 

The  nose  and  throat  of  those  in  attendance  should  be 
sprayed  with  an  antiseptic,  those  containing  thymol 
being  excellent  for  the  purpose.  After  death  the  body 
should  be  encased  in  a  cloth  wetted  with  carbolic  acid 
solution. 


MICROCOCCUS  MENINGITIDIS  93 

In  the  diagnosis  of  this  disease  from  a  bacteriological 
standpoint,  the  most  important  procedure  is  the 
lumbar  puncture.  This  is  the  introduction  of  a  needle 
into  the  meningeal  space  by  entering  between  the 
vertebrae  of  the  lumbar  region.  Its  purpose  is  the 
withdrawal  of  fluid.  This  fluid  is  usually  thin 
turbid  pus  containing  flakes  of  fibrin.  The  turbidity 
is  due  to  great  numbers  of  pus  cells.  These  cells  con- 
tain the  cocci  of  meningitis  which  are  of  the  same 
general  size,  shape,  and  arrangement  as  the  gonococcus. 
They  are  so  like  this  coccus  that  one  must  be  well 
versed  indeed  to  differentiate  between  the  two  without 
a  knowledge  of  the  source  of  the  specimen.  The 
meningitis  cocci  show  a  great  variance  in  size  and 
shape  within  the  same  specimen,  conditions  not  com- 
mon with  the  gonococci.  They  also  stain  differently, 
although  both  are  not  stained  by  the  Gram  method. 
As  is  the  case  with  gonococcus,  they  lie  within  the  pro- 
toplasm, but  not  in  the  nucleus.  Given  a  turbid  fluid 
from  a  case  suggestive  of  meningitis,  it  is  possible  to 
make  a  diagnosis  by  finding  these  cocci.  The  cocci 
may  also  be  found  in  the  blood.  They  develop  agglu- 
tinins  whereby  an  additional  assistance  in  diagnosis 
may  be  given. 

The  cocci  are  grown  with  moderate  ease  on  labor- 
atory media  especially  if  they  contain  blood  serum  or 
glucose.  They  grow  best  in  the  presence  of  oxygen, 
at  37.5°  C.  or  98°  R,  but  die  rapidly  if  not  put  on 
fresh  food  frequently.  They  will  live  a  considerable 
time  in  the  ice-box,  unlike  the  gonococcus. 

They  are  killed  by  heating  to  50°  C.  or  122°  F.  for 
ten  minutes,  by  exposure  to  sunlight  at  once,  and 


94     LOCALIZED  INFECTIONS  OF  PUS  NATURE 

by  almost  all  disinfectants  in  appropriate  strength  in 
five  minutes. 

Antimeningitis  Serum. — Meningitis  cocci  belong  to 
the  bacteria  which  produce  endotoxins.  As  anti- 
bodies to  this  toxin,  agglutinins  and  antibacterial 
bodies  or  bacteriolysins  are  formed.  The  endocellular 
poisons  are  the  bodies  responsible  for  the  peculiar 
effects  of  these  cocci,  and  there  have  been  many 
experiments  with  the  object  of  finding  a  serum  which 
will  counteract  the  effect  of  this  part  of  the  organism. 
Animals  are  not  very  susceptible  to  the  meningitis 
coccus,  but  at  last  it  was  found  that  the  poison  ex- 
tracted from  the  bodies  by  letting  them  disintegrate  in 
water,  would  poison  animals.  Therefore,  by  starting 
with  minute  non-poisonous  doses  and  rising  in  quantity 
and  strength  it  was  possible  to  procure  a  serum  from 
goats  which  was  protective  or  neutralizing  when  mixed 
with  a  dose  of  the  poison  sufficient  alone  to  affect  an 
unprepared  animal.  This  is  immunizing  actively  to 
procure  a  serum  to  be  injected  into  another  animal 
(human  being)  to  immunize  it  passively.  The  use  of 
such  a  serum  has  met  with  great  success  both  here 
and  abroad,  and  the  mortality  of  the  disease  has  been 
greatly  reduced. 

DIPLOCOCCUS    (STREPTOCOCCUS)    PNEUMONIA 

Pneumonia  or  inflammation  of  the  lungs  may  be 
caused  by  a  great  many  organisms,  but  by  far  the 
commonest  one  is  the  Diplococcm  or  Streptococcus  pneu- 
monicB  or  pneumococcus.  This  omnipresent  organism 
gains  entrance  to  the  body  almost  exclusively  by 


DIPLOCOCCUS  PNEUMONIA  95 

the  nose  or  mouth.  It  enters  the  air  passages  and 
penetrates  to  the  finer  parts  of  the  lungs,  there  setting 
up  a  rather  characteristic  inflammation.  In  certain 
types  of  pneumonia  the  disease  may  involve  whole 
lobes;  again,  small  patches  here  and  there  may  be 
involved,  the  intervening  tissue  being  practically 
normal.  From  the  lungs  the  bacteria  naturally  pene- 
trate into  the  blood  stream.  This  emphasizes  the  fact 
that  while  pneumonia  expresses  itself  chiefly  in  the 
lungs,  it  is  in  reality  a  general  infection.  It  should, 
moreover,  be  included  among  the  transmissible  infec- 
tions because  it  appears  in  epidemics  and  definite 
instances  of  communication  directly  from  the  sick  to 
the  well  are  known. 

By  reason  of  the  spread  of  pneumococci  through  the 
blood,  complications  in  the  form  of  involvement  of 
nearly  every  tissue  in  the  body  may  result.  The 
interior  of  the  heart,  the  pleura,  and  the  meninges 
are  most  commonly  affected. 

For  diagnosis  bacteriologically,  cultures  are  made 
from  the  sputum,  selecting  the  blood-streaked  speci- 
mens, and  of  the  blood.  Sputum  should  be  dis- 
infected by  receiving  it  directly  in  5  per  cent,  car- 
bolic solution.  If  cloths  are  used  to  wipe  the  mouth, 
they  should  be  burned.  This  is  the  chief  method  for 
protecting  the  well.  Rinsing  the  throat  with  a  mild 
antiseptic  is  advisable  both  for  patients  and  nurses. 

The  coccus  belongs  properly  to  the  streptococci, 
since  it  divides  only  in  one  plane,  and  its  cultures  may 
appear  in  chains.  It  has  the  peculiarities  of  growing  in 
an  oval  shape  in  pairs,  with  the  distal  ends  pointed 
(lance-shape),  and  being  surrounded  by  a  capsule. 


90     LOCALIZED  INFECTIONS  OF  PUS  NATURE 

This  shape  and  envelope  are  quite  characteristic,  and 
almost  determinative.    The  coccus  grows  very  slightly 


FIG.  29 


Pneumococcus  from  bouillon  culture,  resembling  streptococcus.     (Park.) 
FIG.  30 


Pneumococci    in   peritoneal    pus.     Stained  with  fuchsin.      X  1000  diameters 
Clear  spaces  indicate  capsules.     (Park.) 

on  ordinary  culture  media,  but  best  when  blood  or 
blood  coloring  matter  is  added.     It  then  produces  a 


DIPLOCOCCUS  PNEUMONIA  97 

faint  green  color  and  grows  best  at  37°  C.  or  98°  F.,  but 
does  not  live  long,  requiring  repeated  transference  to 
fresh  food.  In  sputum  the  pneumococcus  may  remain 
alive  and  capable  of  producing  disease  for  several 
months  if  protected  from  light.  If  the  sputum  be 
dried  and  powdered,  so  that  it  could  be  inhaled,  the 
cocci  live  for  a  few  days  in  diffused  light.  Direct 
sunlight  kills  them  almost  immediately.  They  are 
killed  at  52°  C.  or  126°  F.  in  ten  minutes.  It  is  said 
that  the  best  way  to  disinfect  sputum  is  by  the  addition 
of  about  one-third  alcohol.  The  pneumococcus  itself 
has  a  very  low  resistance  to  any  of  the  ordinary 
disinfectants,  being  killed  in  a  few  minutes. 

Most  of  the  lower  animals,  particularly  mice  and 
rabbits,  but  not  birds,  are  susceptible  to  the  pneumo- 
coccus. But  a  true  pneumonia  as  seen  in  man  has 
not  been  produced  artificially.  The  pneumococcus 
produces  a  small  quantity  of  poison  aside  from  itself, 
but  acts  chiefly  by  reason  of  substances  within  the 
germ  cell.  The  resistance  of  animals  to  the  pneumo- 
coccus can  be  increased  by  repeated  injections,  but 
the  serum  of  such  has  no  value  in  the  treatment  of 
pneumonia.  The  use  of  vaccines  has  not  been  followed 
by  uniformly  favorable  results.  The  blood  in  pneu- 
monia contains  some  agglutinins,  but  they  are  not  of 
much  value  in  diagnosis. 


CHAPTER    IX 
THE  ACUTE  SELF-LIMITED  INFECTIONS 

IN  this  chapter  are  included  the  infectious  diseases 
which  are  due  to  a  specific  microorganism  and  which 
tend  to  run  a  definite  clinical  course. 

BACTERIUM  DIPHTHERIA 

Diphtheria  is  a  disease  characterized  by  the  develop- 
ment of  a  so-called  false  membrane  upon  a  mucous 
membrane  or  abraded  surface,  caused  by  the  Bacterium 
diphtheria,  or  diphtheria  bacillus,  or  Klebs-Loffler 
bacillus,  from  which  the  soluble  poisons  are  absorbed 
by  the  circulation.  This  false  membrane  is  an  inflam- 
matory exudate  thrown  out  by  the  body  under  the 
stimulus  of  the  bacteria,  as  a  means  of  protection 
against  them.  Myriads  of  bacteria  are  included  in 
the  meshes  of  this  exudate.  If  the  false  membrane 
be  removed  a  raw  bleeding  surface  is  exposed.  Some- 
times this  is  done  for  the  purpose  of  applying  remedial 
agents.  The  false  membrane  of  diphtheria  appears 
most  commonly  upon  the  throat  and  nose,  but  it  may 
be  found  upon  the  eye,  vagina,  or  skin  wound. 

This  is  the  disease  par  excellence  for  explaining  the 
effect  of  toxins,  extracellular  and  separable  from  the 
bacteria.  The  organisms  do  not  enter  the  body,  but 
only  their  toxins  are  absorbed  and  are  responsible 


BACTERIUM  DIPHTHERIA  99 

for  the  clinical  symptoms  of  illness.  These  are  moder- 
ate fever  with  rapid  pulse,  and  great  prostration. 
They  are  also  responsible  for  the  paralyses  which 
frequently  follows  an  attack,  such  as  heart  weakness 
or  laryngeal  failure. 

Diphtheria  is  contracted  by  receiving,  on  a  suscep- 
tible surface,  some  of  the  bacteria  themselves.  They 
usually  come  from  an  active  case.  However,  after 
recovery  from  the  attack  at  a  time  when  no  symptoms 
exist,  fully  virulent  bacteria  may  remain  in  the  throat 
for  many  days.  People  with  such  a  condition  are 
called  "carriers,"  and  strict  hygienic  measures  are 
being  taken  now  by  all  health  authorities  to  prevent 
spread  of  the  disease  by  such  means.  Coughing  or 
sneezing  dislodges  particles  containing  diphtheria 
bacilli,  and  spreads  the  disease.  Infection  has  been 
known  to  travel  by  milk,  where  the  dairyman  had 
a  case  on  his  farm.  The  milk  had  become  infected 
by  those  handling  it.  Nurses  and  doctors  contract 
the  disease  frequently  by  their  close  association  with 
the  patient.  The  absolute  isolation  of  patient  and 
nurse  is  now  demanded  by  health  authorities. 

All  materials  that  can  be  so  treated  should  be 
burned.  Utensils  and  fabrics  should  be  soaked  in 
carbolic  acid  solution  and  then  boiled.  Great  care 
must  be  used  by  the  nurse  with  her  hands,  face,  nose, 
throat,  hair,  and  clothes.  The  lodgement  of  diph- 
theria bacilli  in  the  hair  is  of  special  danger,  since  they 
remain  active  for  a  long  time.  To  prevent  the  settling 
of  the  bacilli  in  the  hair  it  is  advisable  to  wear  a  cap 
that  will  completely  cover  the  head.  Thorough  wash- 
ing with  soap  and  water,  rinsing  in  hydrogen  peroxide, 


100     THE  ACUTE  SELF-LIMITED  INFECTIONS 

5  per  cent.,  and  drying  in  the  sun  are  demanded  when 
the  nurse  leaves  the  patient.  The  nurse  should 
receive  immunizing  doses  of  antitoxin.  Since  the 
bacilli  spread  through  the  air,  sheets  wetted  with 
disinfectants  should  be  hung  about,  particularly  at 
doors. 

FIG.  31 


A. 


Bacterium  diphtheria:  A,  its  morphology  on  glycerin-agar-agar;  B,  its 
morphology  on  Loffler's  blood  serum;  C,  its  morphology  on  acid  blood  serum 
mixture.  (Abbott.) 


For  diagnosis  of  diphtheria  use  is  made  of  direct 
examination  of  stained  smears  from  the  site  of  trouble, 
and  cultures  upon  blood  serum,  the  best  culture 
medium. 

The  bacilli  are  rather  characteristic  in  their  irregular 
shape.  They  are  rods  of  unequal  length  and  width, 
full  of  granules,  which  stain  more  deeply  than  the  rest 


BACTERIUM  DIPHTHERIA  101 

of  the  rod.  Their  ends  are  usually  clubbed  or  the 
whole  rod  may  have  the  shape  of  a  wedge.  They  may 
be  straight  or  bent.  They  vary  from  TOTOT  to  Tinnr 
of  an  inch  in  length,  and  from  5~oiro"o  to  2~5iroiy  of  an 
inch  in  breadth.  They  are  very  apt  to  show  peculiar, 
more  or  less  characteristic  forms  of  degeneration.  A 
special  stain  called  Loffler's  alkaline  methylene  blue 
solution  is  used  to  show  the  peculiarities  of  their 
structure.  The  diphtheria  bacilli  are  non-motile, 
non-spore-bearing  rods.  They  are  not  pronounced  in 
their  manifestations  of  life  under  artificial  conditions, 
except  for  toxin  production,  but  they  grow  readily 
on  most  laboratory  culture  media.  Solidified  blood 
serum  is  the  preferred  artificial  foodstuff.  Upon  it  they 
grow  in  such  a  manner  as  to  render  diagnosis  easy, 
both  by  the  naked  eye  appearance  and  their  shapes 
under  the  microscope.  These  bacilli  grow  best  at  the 
body  temperature,  37°  C.  or  98°  F.,  but  also  at  a 
lower  point. 

They  are  killed  at  58°  C.  or  140°  F.  for  ten  minutes. 
Boiling  kills  in  one  minute.  In  the  dry  state,  protected 
from  daylight,  these  organisms  may  live  several  months. 
With  such  protection,  when  moist  or  in  exudate,  as 
from  the  throat,  life  may  persist  for  at  least  four 
months.  Direct  sunlight  kills  within  half  an  hour. 
On  cloth  or  other  absorbing  material  their  life  is  long, 
but  indeterminate.  On  coins  they  die  in  twelve  to 
thirty-six  hours.  On  toys,  lead,  and  slate  pencils  and 
tumblers  they  may  live  several  weeks.  They  do  not 
live  long  in  cultures  unless  frequently  transferred  to 
fresh  food.  They  resist  cold.  These  data  concerning 
the  viability  of  the  Klebs-Loffler  bacillus  in  the  outer 


102      THE  ACUTE  SELF-LIMITED  INFECTIONS 

world  help  to  explain  the  sudden  and  otherwise  inex- 
plicable outbreaks  of  diphtheria,  and  the  difficulties 
of  their  eradication.  To  disinfectants  they  present 
a  slightly  greater  resistance  than  most  non-spore- 
bearing  bacilli.  Carbolic  acid,  1  to  100,  kills  in  ten 
minutes;  corrosive  sublimate,  1  to  1000,  in  twenty 
minutes.  Hydrogen  peroxide  kills  them  rather  easily. 
These  figures  are  for  bacteria  suspended  in  water. 

Diphtheria  bacilli  will  kill  most  experimental 
animals,  but  the  guinea-pig  is  the  most  susceptible. 
Here  they  characteristically  produce  a  sloughing  at 
the  site  of  inoculation,  a  peritonitis,  and  a  congestion 
of  the  adrenal  gland.  Sometimes  organisms  suggestive 
of  diphtheria  bacilli  are  found  in  the  throat  without  a 
membrane.  In  order  to  prove  if  these  be  true  diph- 
theria forms,  some  of  a  culture  is  injected  under  the 
skin  of  a  guinea-pig.  If  the  changes  described  are 
produced,  and  the  animal  dies  in  three  days,  it  shows 
that  the  organism  in  question  was  a  true  virulent 
diphtheria  bacillus. 

Diphtheria  Antitoxin. — The  specific  poison  of  the 
organisms  and  the  means  used  to  neutralize  it  must 
now  be  discussed.  The  poison  of  the  diphtheria  bacillus 
is  not  only  made  in  the  false  membrane  in  the  human 
case,  but  is  elaborated  by  the  organism  in  artificial 
media  in  a  laboratory.  This  poison  itself  will  kill  the 
lower  animals.  The  toxin  is  obtained  by  growing  the 
germs  on  broth,  made  in  a  manner  found  most  suitable 
for  its  development.  The  broth  is  freed  of  bacterial 
bodies  and  injected  into  horses.  This  animal  is  chosen 
for  its  size  and  freedom  from  disease  affecting 
humans,  and  because  large  quantities  of  material  may 


BACTERIUM  DIPHTHERIA  103 

be  injected  and  much  blood  withdrawn  without 
harming  the  beast.  The  horses  receive  under  the 
skin  gradually  increasing  quantities  of  this  toxic  broth 
until  they  are  able  to  withstand  huge  quantities, 
many  times  the  quantity  necessary  to  kill  them  if 
given  at  first.  They  are  then  considered  to  have 
some  neutralizing  substances  for  this  toxin.  This 
neutralizing  property  is  known  to  be  in  the  blood 
serum.  The  horse  is  then  bled,  and  the  serum  separ- 
ated from  the  red  blood  cells.  It  is  then  tested  against 
the  original  toxin  used  for  making  the  injections.  This 
is  done  by  mixing  the  two  in  definite  parts,  allowing 
the  mixture  to  stand  a  few  minutes,  and  injecting  it  into 
guinea-pigs.  By  appropriate  technique  the  number  of 
"units"  is  determined.  A  "unit"  is  that  quantity  of 
horse  serum,  or  antitoxin,  which  will  neutralize  100 
times  the  smallest  quantity  of  toxin  necessary  to  kill  a 
guinea-pig  weighing  250  grams  (8i  ounces). 

The  horse  serum  antitoxin  has  now  a  value  for  clinical 
purposes,  as  the  quantity  to  be  given  can  be  controlled. 
Newer  methods  have  permitted  the  refinement  and 
concentration  of  this  antitoxin,  so  that  there  is  now 
less  inconvenience  in  giving  it.  The  dose  for  treatment 
varies  from  1500  to  5000  units  by  injection  under  the 
skin.  In  bulk  this  may  be  less  than  a  teaspoonful. 
For  immunizing  purposes,  that  is,  to  protect  persons 
exposed  but  not  yet  suffering  from  the  disease,  from 
300  to  1000  units  are  used.  In  both  cases  a  repetition 
of  the  dose  iis  frequently  demanded,  and  in  case  the 
exudate  does  not  fade,  the  injections  may  have  to 
be  given  several  times.  The  effect  is  a  passive  acquired 
immunity,  as  it  is  the  addition  of  a  toxin-neutralizing 


104     THE  ACUTE  SELF-LIMITED  INFECTIONS 

substance  to  aid  tissues  for  which  they  themselves 
have  not  worked.  The  visible  effects  of  antitoxin 
administrations  are  a  rather  rapid  disappearance  of 
the  false  membrane,  a  fall  of  temperature,  and  a 
lessening  of  constitutional  prostration. 

For  the  best  results  in  the  treatment  of  diphtheria, 
antitoxin  should  be  used  early.  Each  hour  of  delay 
in  using  it  after  the  diagnosis  has  been  made  reduces 
the  good  chances  of  the  patient.  For  large  cities  the 
decrease  in  mortality  has  been  50  per  cent.,  and  in 
the  favorable  cases,  even  75  per  cent. 

Serum  Sickness.— Sometimes  what  is  called  serum 
sickness  occurs  after  antitoxin  injections.  This  con- 
sists in  a  general  feeling  of  illness,  with  skin  eruptions, 
swelling  of  the  glands,  edema,  and  albumin  in  the 
urine.  It  occurs  in  susceptible  individuals,  and  its 
cause  is  unknown.  Some  ascribe  it  to  a  peculiar 
phenomenon  of  also  unknown  nature,  called  anaphy- 
laxis,  not  necessary  to  describe  here.  Occasionally 
sudden  death  has  occurred.  The  fatal  cases  are 
said  to  have  been  in  individuals  susceptible  to  the 
presence  of  horses. 

Pseudodiphtheria  Bacilli. — There  is  a  group  of  organ- 
isms called  pseudodiphtheria  bacilli,  because  of  their 
resemblance  in  morphology  and  growth  to  the  true 
disease-producing  type.  They  are  sometimes  found 
in  jaw  abscesses  or  otitis  media.  They  do  not  produce 
the  typical  diphtheritic  sore  throat.  The  presence  of 
such  forms  in  the  throat  often  leads  to  erroneous 
diagnoses,  and  lengthens  quarantine.  Quarantine  is 
demanded  by  health  authorities  until  the  throat  is 
shown  to  be  clear  of  diphtheria  bacilli  for  two  successive 
days. 


BACILLUS  TETANI  105 

BACILLUS  TETANI 

Tetanus  or  lockjaw  is  a  disease  characterized  by 
tonic  and  clonic  spasms  of  the  muscles  due  to  the  effect 
of  the  soluble  poisons  of  the  Bacillus  tetani  or  tetanus 
bacillus  upon  the  central  nervous  system.  This 
poison,  like  that  of  the  diphtheria  germ,  is  separable 
or  extracellular.  It  is  produced  by  the  bacteria, 
absorbed  along  the  motor  nerves,  and  carried  to  the 
brain  and  cord.  Tetanus  bacilli  enter  the  body  almost 
invariably  by  punctured  or  lacerated  wounds.  They 
multiply  in  the  deep  covered  position  afforded  by  such 
wounds,  but  are  not  themselves  taken  up  by  the  blood 
to  be  distributed  throughout  the  body,  only  their 
poisons  being  absorbed.  The  bacteria  are  common  in 
soil,  manure,  dust  from  covered  places,  wood,  and  the 
like. 

Their  vitality  is  considerable,  due  to  the  formation 
of  resistant  spores.  Wounds  carry  the  germs  beneath 
the  skin,  where  they  lie  covered  and  hidden  in  the 
deeper  tissues.  They  do  not  grow  in  the  presence  of 
oxygen  (anaerobic),  so  that  their  secluded  place  in  the 
depths  of  wounds  favors  their  development  and  that 
of  their  toxin.  If  other  germs  are  introduced  the  tissues 
are  further  devitalized  by  them,  and  favorable  con- 
ditions for  tetanus  increased.  Either  spores  or  vege- 
tating germs  may  be  introduced  on  rusty  nails,  splinters 
of  wood  or  glass,  blank  cartridge  plugs,  or  the  grinding 
of  dirt  into  wounds.  Tetanus  sometimes  appears  in 
the  newborn  or  in  the  puerperal  mother,  particularly 
after  instrumental  delivery.  Ordinary  gelatine  is  said 
to  often  contain  spores. 


106     THE  ACUTE  SELF-LIMITED  INFECTIONS 

Between  the  time  of  introduction  of  the  germs 
and  the  outbreak  of  symptoms  a  period  of  incuba- 
tion elapses  which  may  be  as  short  as  three  days  or 
as  long  as  six  weeks.  The  muscles  nearest  the  wound 
are  affected  first,  as  a  rule,  but  the  characteristic 
symptoms  of  lockjaw  soon  appear.  After  death  very 
little  is  to  be  found  by  postmortem. 

The  danger  from  patients  with  tetanus  is  quite 
inconsiderable,  the  only  infective  material  being  the 
discharges  from  the  wound  or  the  pieces  cut  away 
surgically.  Such  objects  are  used  for  injection  into 
animals  to  establish  a  diagnosis.  This,  however,  is 
seldom  necessary,  as  tetanus  is  quite  clear  in  its  symp- 
tomatology. All  dressings  and  pieces  removed  sur- 
gically must  be  burned  with  actual  fire.  Boiling  and 
baking  are  unreliable.  The  first  treatment  usually 
undertaken  is  the  surgical  cutting  away  of  skin  and 
subcutaneous  tissue  far  beyond  the  original  wound,  in 
order  to  remove  all  bacilli.  If  these  are  removed  no 
more  toxin  can  be  made. 

The  tetanus  bacillus  is  large,  TTSTTO  to  Woo"  mcn 
long  by  ^"oioT to  "SWOT  inch  wide;  it  is  a  motile,  spore- 
bearing  bacillus,  growing  only  when  the  atmospheric 
oxygen  is  shut  out.  The  motility  is  due  to  flagella 
arranged  all  about  the  cell  wall.  The  spores  develop 
at  one  end  and  give  the  rod  a  drumstick  appearance. 
They  are  best  seen  in  old  cultures.  The  spores  may 
leave  the  parent  bacillus  and  lead  an  independent 
existence.  In  this  state  they  are  not  motile,  and  are 
stained  with  great  difficulty.  The  vegetative  rod, 
however,  stains  with  comparative  ease.  The  organism 
can  digest  gelatine  and  grows  characteristically  in  it. 


BACILLUS  TETANI  107 

In  discussing  the  resistance  of  this  germ  to  deleterious 
agents,  the  spores  only  need  be  considered,  because 
the  vegetative  rod  has  the  power  of  going  into  this 
resistant  stage  very  quickly  when  it  meets  unfavorable 
environment.  The  rods  grow  best  at  38°  C.  or  98°  F. 
The  spores  are  killed  at  105°  C.,  221°  F.,  when  exposed 
ten  minutes  to  streaming  steam.  They  are  destroyed 
by  chemicals  as  follows:  5  per  cent,  carbolic  acid  in 
ten  hours;  5  per  cent,  carbolic  acid  plus  0.5  per  cent. 

FIG.  32 


Tetanus  bacilli  with  spores  in  distended  ends.     X  1100  diameters.     (Park.) 

hydrochloric  acid  in  two  hours;  1  to  1000  corrosive 
sublimate  in  three  hours;  1  to  1000  corrosive  sublimate 
plus  0.5  per  cent,  hydrochloric  acid  in  one-half  hour; 
1  per  cent,  silver  nitrate  in  five  minutes.  When  dried 
the  tetanus  spores  will  live  several  years.  Sunlight 
very  slowly  kills  them.  Most  animals  are  susceptible 
to  the  tetanus  bacillus  or  its  toxins.  Rats  and  birds 
are  the  least,  while  horses  and  man  are  the  most 
sensitive. 


108     THE  ACUTE  SELF-LIMITED  INFECTIONS 

Tetanus  Antitoxin. — The  toxin  of  the  tetanus  bacillus 
is  one  of  the  most  virulent  poisons  known.  For  ex- 
ample, Trnmnnnr  cubic  centimeter  or  e^oVor  minim 
has  been  known  to  kill  a  mouse.  -It  is  composed 
of  two  parts,  one  the  major,  with  a  primary  irri- 
tating and  secondary  paralyzing  effect  on  the  cen- 
tral nervous  system,  and  a  minor  part  having  a 
solvent  action  upon  the  red  blood  cells.  These  poisons 
develop  both  in  wounds  and  on  laboratory  culture 
media.  The  methods  for  procuring  this  poison  are 
essentially  those  described  under  diphtheria,  and 
similar  methods  are  used  to  immunize  horses  against 
it.  The  antitoxin  is  in  the  immunized  horse's  serum, 
and  is  refined  and  used  in  the  same  general  manner  as 
diphtheria  antitoxin.  The  unit  in  this  case  is  the  quan- 
tity of  antitoxin  necessary  to  neutralize  1000  times  the 
smallest  dose  of  toxin  required  to  kill  a  guinea-pig 
weighing  350  grams,  llf  ounces.  The  conditions  of 
administering  antitoxin  for  tetanus  are  somewhat  dif- 
ferent from  those  in  diphtheria.  In  the  latter  the  poison 
is  largely  circulating  in  the  blood,  while  in  tetanus  some 
of  it  is  at  the  point  of  infection,  some  in  the  muscles  and 
nerves  and  central  nervous  system,  and  the  least  part  is 
in  the  blood.  To  reach  all  of  these  places  it  is  necessary 
to  make  injections  into  the  vein  and  under  the  skin 
as  well.  The  surgeon  attempts  to  reach  those  parts 
first  which  have  been  affected  the  longest,  to  halt  at 
once  any  further  damage  there,  and  therefore  methods 
of  treatment  vary.  Antitoxin  is  sometimes  injected 
directly  into  the  nerves  in  order  that  some  may  neu- 
tralize what  toxin  is  remaining  in  them  along  their 
length  or  in  their  muscle  distribution. 


BACILLUS  TYPHOSUS  109 

It  is  best  to  give  10,000  units  by  the  vein  and 
repeat  at  several  hour  intervals  until  symptoms  start 
to  abate.  The  sooner  after  the  symptoms  appear 
that  antitoxin  is  given  the  more  favorable  is  the 
outlook.  Antitoxin  is  now  given  freely  by  health 
authorities,  to  all  who  receive  firearm  wounds  about 
July  4. 

BACILLUS  TYPHOSUS 

Typhoid  fever  or  enteric  fever  is  an  acute  infectious 
disease  caused  by  the  Bacillus  typhosus  or  typhoid 
bacillus  circulating  in  the  blood  and  settling  in  the 
various  organs,  particularly  the  lymphatic  structures 
of  the  small  intestines. 

The  bacteria  enter  the  body  via  the  mouth  and  are 
able  to  pass  the  stomach  into  the  small  intestines. 
Here  they  are  taken  up  by  the  lymphatic  organs, 
which  immediately  begin  to  swell.  This  reaction 
brings  more  blood  to  the  part  and  the  circulation  soon 
contains  the  germs.  The  incubation  period  is  that 
time  elapsing  between  the  introduction  of  the  typhoid 
bacillus  into  the  alimentary  canal  and  the  first  positive 
signs  that  it  has  been  taken  up  and  disseminated  by 
the  blood  stream.  Then  there  are  gradually  increasing 
fever,  malaise,  a  relatively  slow  pulse,  distention  of 
the  abdomen,  diarrhea  or  constipation,  rose  spots,  and 
other  signs  of  the  true  infection.  The  incubation  is 
about  two  weeks.  The  bacteria,  while  not  true  pus- 
formers,  do  cause  a  breaking  down  of  tissue.  This  is 
characteristically  seen  in  the  lymphatics  of  the  small 
intestine  called  Peyer's  plaques.  These  bodies  swell 
toward  the  free  lumen  of  the  canal,  'and  the  centre 


110      THE  ACUTE  SELF-LIMITED  INFECTIONS 

finally  softens  from  the  effect  of  the  bacilli.  When 
the  softened  part  separates  and  is  removed,  a  ragged, 
punched-out  ulceration  remains.  This  ulceration  may 
be  progressive  and  eat  into  bloodvessels,  causing 
intestinal  hemorrhage  so  common  in  this  disease.  If 
the  ulceration  be  directed  out  toward  the  peritoneal 
surface  of  the  intestine,  perforation  and  peritonitis 
may  ensue.  The  presence  of  the  typhoid  bacilli  and 
their  toxins  in  the  organs,  notably  the  spleen,  causes 
characteristic  changes  which  need  not  be  dwelt  upon 
here. 

Typhoid  fever  is  more  common  in  men  between  the 
ages  of  twenty  and  thirty-five  years.  Spring  and 
autumn  are  the  seasons  of  greatest  prevalence.  It 
spreads  from  patient  to  patient  usually  through  the 
intervention  of  food  and  drink.  Polluted  water  and  food 
infected  by  flies  that  have  soiled  their  bodies  upon  ex- 
creta, form  the  greatest  sources  of  indirect  propagation. 
Water  is  polluted  by  the  dumping  of  sewage  containing 
typhoid  germs  into  a  water  course  used  as  a  drinking 
supply.  Typhoid  bacilli  can  live  within  a  particle  of 
feces  over  the  winter,  so  that  the  infection  of  a  water 
course  in  the  spring  is  not  to  be  wondered  at.  When 
winter  breaks  up  the  spring  rains  wash  down  the  hill- 
sides, sweeping  before  them  surface  collections  into 
streams.  The  greatest  danger,  however,  exists  when 
towns  empty  their  sewerage  systems  into  a  stream 
from  which  other  communities  lower  down  take  their 
domestic  supply.  This  means  of  spread  is  proven  by 
the  fact  that  when  known  infected  sewage  is  no  longer 
dumped  into  a  water  supply  typhoid  fever  ceases 
to  be  prevalent  among  the  users  of  the  water.  Ice  is 


BACILLUS  TYPHOSUS  111 

said  to  be  another  method  of  transmitting  this  disease. 
It  is  best  not  to  inculpate  the  ice  itself,  since  freezing 
kills  whatever  germs  are  not  squeezed  out  in  the  con- 
traction of  the  water  when  becoming  solid,  but  rather 
blame  the  dirty  methods  of  cutting,  storing,  and 
distributing.  Ice  not  infrequently  becomes  covered 
with  manure  and  earth  in  storing,  and  lading  for 
distribution.  The  unwashed  hands  of  the  ice-man  are 
only  too  familiar.  When  ice  is  placed  in  the  water 
cooler  in  public  places  it  is  frequently  washed  under  a 
spigot  and  then  picked  up  in  the  hands  of  the  distributor. 

Typhoid  bacilli  do  not  multiply  to  any  considerable 
extent  in  water,  but  merely  remain  viable.  Milk  is 
a  prolific  source  of  spread,  since  it  is  easy  for  the 
dairyman  with  a  case  of  typhoid  on  his  farm  to  infect 
this  product.  Fresh  milk  has  a  mild  restraining 
effect  upon  typhoid  germ  growth,  but  does  not  kill 
many.  The  bacilli  do  not  come  from  the  cow,  but 
are  introduced  somewhere  in  the  route  from  her  to  the 
consumer.  Vegetables  grown  in  ground  upon  which 
infected  manure  or  water  has  been  spread  may  carry 
the  disease ;  such  are,  for  instance,  water-cress,  lettuce, 
tomatoes,  or  others  that  are  eaten  raw.  Oysters 
fattened  in  water  contaminated  by  sewage  are  said  to 
transmit  the  disease. 

House-flies  may  settle  upon  human  excreta  in  out- 
houses or  toilets  or  in  sick-rooms,  and  by  walking  on 
articles  intended  for  food,  leave  behind  some  of  the 
germs. 

The  personal  contact  of  nurse,  physician,  or  a  member 
of  the  family  must  never  be  underestimated  as  a  means 
of  direct  transmission.  Indeed,  it  is  looked  upon  by 


112     THE  ACUTE  SELF-LIMITED  INFECTIONS 

some  authorities  as  the  most  important  and  fruitful 
method.  Upon  bed-pans,  glasses,  eating  utensils,  bed 
linen,  or  clothes  there  may  be  a  few  bacilli  lurking, 
which  can  easily  be  conveyed  to  the  mouth  by  persons 
handling  these  objects. 

Measures  for  preventing  infection  should  be  directed 
toward  killing  all  the  typhoid  bacilli,  not  such  a  diffi- 
cult task.  Infective  material  consists  of  feces,  urine, 
expectoration,  and  possibly,  perspiration.  Any  of  these 
may  infect  bed  or  body  linen,  and  the  last  can  spread 
the  bacilli  on  dishes  or  hands.  All  discharges  should 
be  received  in  carbolic  acid  solutions,  well  mixed  and 
allowed  to  stand  half  an  hour  before  emptying  into  a 
drain.  Clothing  of  all  kinds  should  be  soaked  in  carbolic 
or  corrosive  sublimate  solution  for  an  hour,  and  then 
boiled.  The  same  procedure  should  be  followed  with 
glasses  and  eating  utensils.  The  mouth  should  be 
washed  or  wiped  with  boric  acid  solution  frequently. 
A  dish  of  bichloride,  1  to  2000,  should  be  convenient, 
so  that  the  nurse  or  visitor  may  cleanse  the  hands 
frequently. 

The  typhoid  bacilli  may  lurk  in  the  body,  probably 
in  the  bile  passages,  for  a  long  time  after  the  attack. 
For  this  reason  disinfection  of  stools  and  urine  should 
be  continued  for  at  least  two  months  after  the  patient 
is  well.  Such  people  as  may  spread  the  disease  by 
this  means  are  called  "carriers" 

The  typhoid  bacillus  is  an  organism  exerting  its 
noxious  power  by  means  of  poisons  contained  in  its 
body  and  liberated  upon  its  disintegration.  These 
endocellular  poisons  are  capable  of  calling  forth  a 
reaction  upon  the  part  of  the  body  which  results  in 


BACILLUS  TYPHOSUS 


113 


some  antibody  formation.  Second  attacks  of  typhoid 
are  rare  and  the  reason  is  probably  that  a  sort  of 
active  immunity  is  gained  by  one  attack.  As  a  matter 
of  fact,  it  can  be  shown  by  laboratory  methods  that 
blood  after  typhoid  fever  has  more  power  to  destroy 
the  bacilli  than  before  the  attack.  That  is,  it  has 
more  bacteriolysin  than  is  possessed  by  the  blood  of 
a  person  who  has  never  suffered  from  typhoid. 

FIG.  33 


Microscopic  field,  showing  the  top  of  a  hanging  drop  in  a  normal  typhoid 
culture.  (Park.) 


Widal  Test. — Far  more  important  antibodies  are 
the  agglutinins  used  extensively  in  the  diagnosis  of 
the  disease.  These  are  "bodies  in  the  blood  which 
when  brought  into  contact  with  the  bacilli,  make  them 
stop  moving  and  clump  together.  To  use  this  for 
diagnostic  purposes  a  fluid  culture  or  salt  solution  sus- 
pension of  the  living  actively  motile  germ  is  prepared. 
Some  blood  from  the  patient  is  obtained,  the  clear 
8 


114     THE  ACUTE  SELF-LIMITED  INFECTIONS 

serum  collected  and  mixed  with  the  bacterial  suspen- 
sion in  dilution  of  1  part  of  the  serum  to  20,  50,  100  or 
more  parts  of  the  bacterial  suspension.  These  dilutions 
are  used  because  sera  from  some  persons  entirely  free  from 
typhoid  will  clump  the  bacilli  in  low  dilution,  1  to  5  or 
1  to  10.  The  mixture  of  serum  and  bacteria  is  observed 

FIG.  34 


Microscopic  field,  showing  the  top  of  a  drop  with  the  typhoid  reaction. 
(Park.) 


under  the  microscope  after  they  have  stood  together 
for  a  definite  time,  and  the  presence  of  clumping,  with 
loss  of  movement,  noted.  In  case  this  occurs  typhoid 
is  present.  This  agglutination  reaction  is  called  the 
Widal  test,  and  is  positive  in  about  95  per  cent,  of 
all  cases.  (See  Figs.  33  and  34.) 

Cultures. — It  is  also  of  aid  in  the  diagnosis  of  typhoid 
to  make  a  blood  culture.  This  consists  in  withdrawal, 
under  sterile  conditions,  of  blood  from  a  vein,  placing 


BACILLUS  TYPHOSUS 


115 


it  into  suitable  culture  medium,  and  keeping  it  at  body 
heat  in  the  incubator.  If  typhoid  bacilli  be  present 
they  will  grow  so  that  we  may  isolate  and  identify 
them.  The  bacilli  may  be  isolated  also  from  the 
feces  and  urine  during  an  attack,  and  as  mentioned 
above,  for  a  long  time  afterward  in  the  case  of  carriers. 
The  methods  for  isolation  are  tedious  and  difficult, 
and  need  not  be  described  here.  Many  techniques  have 
been  devised  to  hasten  work  on  epidemics  and  carriers, 
but  none  is  as  yet  very  good. 

FIG.  35 


Typhoid  bacilli  from  nutrient  gelatin.      X  1100  diameters.     (Park.) 


Morphology.  —  The  typhoid  bacillus  is  a  motile  rod 
¥5-11-00-  to  s  TO  0"  inch  long  and  3-  oi  <ro  to  -^WiF  inch  wide, 
with  rounded  ends,  growing  in  long  threads  at  times. 
Its  motility  is  due  to  flagella  all  around  its  cell  wall. 
It  forms  no  spores.  It  stains  easily,  oftentimes  more 
densely  at  the  rounded  ends.  It  grows  in  the  presence 
or  absence  of  oxygen,  best  at  37°  C.  or  98°  F.,  but  also 
at  room  temperature.  It  is  killed  by  heating  at  60°  C. 
or  142°  F.  for  five  minutes,  or  to  52°  C.  or  126°  F.  for 


116     THE  ACUTE  SELF-LIMITED  INFECTIONS 

ten  minutes  when  in  water  solutions.  It  usually  dies 
rapidly  when  dried,  but  occasionally  lives  for  some 
weeks.  It  is  killed  in  watery  suspension  by  1  per  cent, 
carbolic  acid  or  1  to  1000  bichloride  in  ten  minutes.  Its 
characters  in  laboratory  culture  media  are  not  easy  to 
describe,  and  indeed  it  often  puzzles  the  trained  observer 
to  identify  it.  Suspected  cultures  are  usually  subjected 
to  the  Widal  test,  using  the  blood  of  a  patient  with 
typhoid  fever,  and  known  to  clump  a  true  typhoid 

FIG.  36 


Typhoid  bacillus  with  faintly  stained  flagella.     (Loffler's  method.)     (Park.) 

bacillus.  The  bacillus  belongs  to  the  so-called  typho- 
colon  group  (see  p.  164).  The  lower  animals  do  not 
develop  typhoid  fever  when  inoculated  with  this  germ, 
but  die  of  septicemia,  usually  with  peritonitis. 

Immunization. — An  antitoxin  to  the  typhoid  bacillus 
cannot  be  produced,  but  attempts  at  active  immuni- 
zation have  been  made  with  some  success.  These 
attempts  take  the  direction  of  injecting  the  bacilli 
in  such  a  form  that  they  cannot  produce  the  disease, 


BACILLUS  TYPHOSUS  117 

but  yet  set  up  some  resistance  to  it  comparable  to  that 
acquired  by  passing  through  a  spontaneous  attack. 
The  bacilli  are  prepared  like  the  vaccines  or  bacterins 
described  on  p.  82,  and  injected  under  the  skin.  A 
slight  fever  may  result  but  no  further  bad  effects  have 
been  noted.  All  symptoms  are  over  in  twenty-four 
hours  after  each  injection.  The  bacteria  are  intro- 
duced three  times.  The  immunity  resulting  is  sup- 
posed to  last  about  two  years.  This  vaccine  method 
is  well  adapted  for  and  most  used  by  armies  going  into 
camps.  The  results  in  our  army  and  that  of  Great 
Britain  have  been  very  encouraging.  It  should  be 
taken  by  nurses  doing  army  nursing  or  seeing  many 
typhoid  cases. 

Major  Russell,  U.  S.  A.,  concludes  his  investigations 
into  the  theory  and  practice  of  antityphoid  vaccination 
as  a  prophylactic  as  follows : 

1.  Antityphoid  vaccination  in  healthy  persons  is  a 
harmless  procedure. 

2.  It    confers    almost    absolute    immunity    against 
infection. 

3.  It  is  the  principal  cause  of  the  immunity  of  our 
troops  against  typhoid  in  the  recent  Texas  maneuvers. 

4.  The  duration  of  the  immunity  is  not  yet  deter- 
mined, but  is  assuredly  two  and  one-half  years  and 
probably  longer. 

5.  Only  in  exceptional  instances  does  its  administra- 
tion cause  an  appreciable  degree  of  personal  discomfort. 

6.  It  apparently  protects  against  the  chronic  bacillus 
carrier  and  is  at  present  the  only  means  by  which  a 
person  can  be  protected   against  typhoid  under  all 
conditions. 


118     THE  ACUTE  SELF-LIMITED  INFECTIONS 

7.  All  persons  whose  profession  or  duty  involves 
contact  with  the  sick  should  be  immunized. 

8.  The  general  vaccination  of  an  entire  community 
is    feasible    and    could    be    done   without   interfering 
with  general  sanitary  improvements,  and  should  be 
urged  wherever  the  typhoid  rate  is  high. 

Paratyphoid  Fever. — There  is  a  variety  of  enteric 
fever  called  paratyphoid  fever.  This  is  caused  by  the 
Bacillus  paratyphosus,  an  organism  closely  allied  to 
the  true  typhoid  bacillus  and  only  separated  from  it  by 
its  ability  to  ferment  certain  sugars  and  the  quantity 
of  acid  it  produces  under  artificial  conditions.  In  para- 
typhoid fever,  however,  the  blood  will  not  clump 
(agglutinate)  the  true  typhoid  bacillus  but  does  have 
such  an  action  upon  the  paratyphoid  bacillus.  In 
this  form  of  fever  the  course  is  shorter,  the  attack  is 
milder,  and  complications  are  much  less  frequent. 
There  is  usually  no  ulceration  of  Peyer's  plaques  and 
therefore  hemorrhage  from  the  bowel  is  of  extreme 
rarity.  It  is  nevertheless  an  infectious  disease,  entirely 
comparable  in  its  origin,  course,  transmission,  and 
epidemic  character  to  true  typhoid  fever,  and  the  same 
precautions  of  disinfection  must  be  observed. 

BACTERIUM  INFLUENZA 

Influenza  is  also  called  la  grippe  or  grip,  and  is  an 
acute  catarrhal  disease  usually  involving  the  mucous 
membrane  of  the  upper  respiratory  tract,  but  also 
penetrating  to  the  deeper  parts.  Its  causative  bac- 
terium is  the  Bacterium  influenza  or  the  influenza 
bacillus.  The  disease  is  one  which  appears  in  epidemic 


BACTERIUM  INFLUENZA  119 

form  usually,  but  sporadic  cases  also  occur.  The 
organisms  are  carried  in  the  nose  and  throat  and 
communicated  to  others  in  the  fine  particles  coughed 
or  spat  out.  They  lodge  on  the  mucous  surfaces  and 
produce  an  inflammation  through  which  the  poisons 
are  absorbed.  The  rods  themselves  do  not  usually 
enter  the  blood  stream,  and  their  poisons  are  largely 
extracellular.  They  may  enter  the  blood,  as  is  attested 
by  the  fact  that  there  are  influenzal  forms  of  pleuritis 
and  pericarditis,  diseases  probably  not  due  to  an 
extension  by  continuity.  Influenzal  pneumonia  occurs 
when  the  bacteria  penetrate  to  the  lung  tissue  proper. 
It  is  comparable  in  development  to  the  pneumonia 
caused  by  the  pneumococcus.  The  bacillus  may  at 
times  form  pus. 

The  attack  of  influenza  runs  an  acute  course.  It 
leaves  but  a  transient  immunity,  and  one  attack  is  said 
actually  to  predispose  to  another  when  the  individual 
is  exposed  subsequently.  As  complications  of  influenza 
of  the  upper  air  passages  we  may  have  pus  in  the 
sinuses  about  the  nose,  or  otitis  media. 

While  influenza  is  an  acute  disease  and  the  bacteria 
are  actively  virulent  during  an  attack,  it  is  believed 
that  they  remain  in  the  upper  air  passages  in  abey- 
ance and  not  producing  disease  for  long  periods  after 
the  acute  symptoms  have  subsided.  When  they  are 
received  in  sputum  particles  upon  the  nose  or  mouth 
of  another  person  not  resistant  to  them,  they  regain 
their  activity  and  inflame  the  parts.  They  are  said 
to  remain  in  the  lung  tissue  for  a  long  time  until 
some  reduction  of  the  person's  resistance  permits 
the  lighting  up  of  a  pneumonia. 


120      THE  ACUTE  SELF-LIMITED  INFECTIONS 

With  these  facts  in  mind  it  is  not  difficult  to  under- 
stand how  sporadic  cases  occur  and  how  the  disease 
spreads  rapidly  from  one  patient  to  another.  The 
bacilli  get  to  work  on  the  mucous  membranes  rapidly, 
and  the  incubation  period  is  short,  three  days  at  the 
longest.  Epidemics  have  been  known  to  spread  over 
whole  continents  in  a  season.  Many  observers  believe 
that  other  organisms,  notably  streptococci,  help  in 
the  production  of  these  acute  influenzal  colds.  It  is 
undoubtedly  true  that  the  influenza  bacillus  is  seldom 
found  in  pure  culture,  that  is,  in  absence  of  some  other 
organism  with  pathogenic  properties.  The  bacilli  are 
found  in  the  excretions  and  secretions  from  the  nose, 
mouth,  and  lungs.  All  excretions  should  be  received 
into  carbolic  acid  solution,  and  the  mouth  and  nose  fre- 
quently douched  with  a  mild  antiseptic.  The  nurse  and 
members  of  the  family  should  use  care  with  the  nose  and 
mouth  in  frequent  rinsing  with  weak  antiseptics,  such  as 
hydrogen  peroxide.  For  diagnosticating  this  disease 
smears  and  cultures  are  made  from  some  of  the  glaring 
mucus  at  the  back  of  the  throat  or  a  good  specimen  of 
sputum  coughed  from  the  lungs.  The  smears  on  slides 
are  stained  with  appropriate  dyes.  Under  the  micro- 
scope the  delicate  rods  are  found  in  pairs  on  end,  lying 
in  groups  or  within  the  pus  and  epithelial  cells.  In 
cultivating  these  organisms  media  containing  whole 
blood  or  blood  coloring  matter,  hemoglobin,  must  be 
used.  They  will  not  grow  in  the  absence  of  the  latter. 
Their  colonies  upon  solid  media  containing  it  are 
rather  characteristic.  During  an  attack  the  bacteria 
produce  some  agglutinins  in  the  blood  and  the  agglu- 
tination or  clumping  test  may  be  used  with  them. 
This  is  not  highly  practical  and  seldom  used. 


PLATE  III 


Bacterium  Influenzse  in  Sputum.     (Abbott.) 


BACTERIUM  INFLUENZA  121 

The  influenza  organism  is  a  very  minute  rod  with 
pointed  or  round  ends  and  commonly  lying  in  pairs 
with  their  ends  together.  They  do  not  move  nor 
form  spores.  They  measure  about  5~o1ro"o  mcn  l°ng 
and  rooVoo-  to  T5T151F  inch  wide.  They  require 
oxygen  for  growth,  which  occurs  on  blood  containing 
media  as  fine  dewdrop-like  colonies.  Their  general 
biological  characters  offer  fine  details  not  needed 
here.  They  require  body  heat,  37.5°  C.  or  98°  F.,  for 
development,  and  are  killed  at  50°  C.  or  122°  F.  for 
ten  minutes;  60°  C.  or  142°  F.  kills  at  once.  They  die 
in  twelve  hours  if  dried  in  sputum,  but  may  live 
without  multiplication  for  several  days  in  moist 
sputum  at  ordinary  temperature.  Five  per  cent, 
carbolic  acid  kills  them  in  well  mixed  sputum  in  five 
minutes.  For  animals  this  bacterium  is  not  very 
pathogenic.  Rabbits  and  monkeys,  if  injected  into 
the  vein  with  a  pure  culture  exhibit  very  quickly  signs 
of  an  intoxication,  which  rapidly  passes  away.  Mon- 
keys may  get  an  acute  cold  by  the  direct  application 
of  the  bacilli  to  the  abraded  mucous  membrane  of  the 
nose.  No  satisfactory  method  has  as  yet  been  devised 
for  specifically  treating  influenza  patients  with  the 
killed  germs  or  their  antitoxins,  but  it  is  perfectly 
feasible  to  use  bacterin  treatment  since  the  disease  is 
usually  local.  It  is  possible  that  no  immunity  exists 
after  influenza  because  of  the  confinement  of  the  germs 
at  one  place.  Experiments  now  under  way  may  result 
in  something  helpful  for  this  most  annoying  and  some- 
times serious  disease. 


122     THE  ACUTE  SELF-LIMITED  INFECTIONS 

BACILLUS  PESTIS 

Bubonic  plague  or  "the  plague"  or  "pest"  is  an  acute 
infectious  disease  characterized  by  high  fever,  swell- 
ings of  the  regional  lymph  glands,  or  pneumonia,  with 
occasional  hemorrhages  (black  death)  under  the  skin 
in  severe  cases,  caused  by  the  Bacillus  pestis.  The 
disease  is  fostered  by  unhygienic  conditions,  and  may 
be  said  to  be  more  common  in  those  countries  where 
the  people  go  about  scantily  clothed,  especially  about 
the  feet.  There  are  two  forms  of  the  plague,  according 
to  the  place  of  entrance  of  the  bacteria.  The  bubonic 
type  is  that  in  which  painful  swellings  and  abscesses 
occur  in  lymph  glands  when  germs  enter  through  the 
skin  and  the  pneumonic  type  occurs  when  they  are 
inhaled. 

The  bacteria  enter  chiefly  through  the  skin  by  way 
of  minute  wounds,  or  as  was  shown  in  India,  by  the  bite 
of  a  rat  flea,  parasitic  to  man  in  that  country.  Rats  and 
mice,  indeed  all  rodents,  are  susceptible  to  plague  and 
they  contract  it  from  biting  the  living,  feeding  on  the 
dead  and  soiling  themselves  on  dressings  or  excreta. 
When  infected  they  have  great  numbers  of  bacilli  in 
their  blood,  thus  easily  passing  them  on  to  fleas  that  bite 
them.  The  fleas  then  pass  the  disease  to  other  rats 
and  to  man.  Furthermore,  rats  may  vomit,  defecate, 
and  die  where  they  can  infect  objects  later  handled 
by  persons.  The  rats  are  said  to  transmit  the  disease 
also  by  biting  people.  In  epidemic  times  the  ground 
becomes  infected,  and  persons  going  barefoot  may  be 
infected.  By  any  of  the  skin  wound  methods,  the 
germs  enter  the  subcutaneous  tissue,  are  carried  to 


BACILLUS  PEST  IS  123 

the  nearest  lymph  glands,  where  they  set  up  inflam- 
mation and  pus,  which  is  frequently  discharged  by 
rupture  through  the  skin.  The  bacteria  enter  the 
blood  stream  and  produce  a  septicemia. 

1ft  the  pneumonic  form  the  bacteria  are  inhaled  and 
set  up  a  pneumonia  not  unlike  that  produced  by 
ordinary  cocci.  Here  again  there  may  be  suppuration 
and  septicemia. 

The  bacilli  produce  the  characteristic  results  chiefly 
by  means  of  their  endotoxins,  little  or  no  separable 
poisons  being  formed.  There  is  no  difference  in 
the  bacteria  or  their  products  in  the  two  forms 
which  simply  depend  on  their  mode  of  entry.  The 
mortality  of  this  disease  is  very  high,  due  to  the 
rapid  progress  made  after  the  disease  gains  a  foothold. 
The  incubation  is  three  to  seven  days.  The  bacteria 
are  present  in  the  blood,  pus,  and  sputum  in  enormous 
numbers.  They  may  be  also  in  dejecta.  Many  suppose 
them  to  be  in  the  breath,  but  this  is  probably  erroneous. 
They  are  in  the  droplets  of  saliva  expelled  by  cough- 
ing, sneezing,  and  talking.  It  is  customary  in  times 
of  epidemics,  to  go  about  with  a  towel  over  the  nose 
and  mouth,  with  the  feet  and  ankles  well  bound, 
and  all  surfaces  covered.  Sputum,  urine,  and  feces 
should  be  received  into  5  per  cent,  carbolic  acid  and 
allowed  to  remain,  well  mixed,  for  two  hours.  Dress- 
ings from  ulcerated  surfaces  must  be  burned.  Doors 
and  windows  must  be  screened  against  flies  and  mos- 
quitoes. The  room  must  be  rat-  and  mouse-free.  After 
death  formaldehyde  or  carbolic  acid  solution  is  to  be 
injected  into  the  body  entrances  and  applied  about  the 
body  on  the  winding  sheet. 


124      THE  ACUTE  SELF-LIMITED  INFECTIONS 

For  diagnosticating  this  disease  an  abscess  is  punc- 
tured, the  pus  withdrawn,  and  slide  smears  and  cultures 
are  made.  The  bacilli  are  found  in  countless  numbers. 
Cultivation  on  ordinary  media  is  simple.  A  blood 
culture  will  also  reveal  their  presence.  At  death 
bacteria  will  be  found  in  practically  every  organ  in 
the  body. 

The  plague  bacillus  is  a  short  plump  rod,  TT~O"O~O  to 
-nrfor  inch  long  by  ^imnr  to  -girihro  inch  wide.  It  does 
not  move  nor  form  spores.  It  grows  best  at  35°  C. 
or  92°  F.  It  is  stained  with  reasonable  ease,  displaying 
a  peculiar  picture.  The  bacilli  are  short  thick  rods 
with  rounded  ends.  The  end  sections  stain  much 
more  densely  than  the  middle  part,  called  bipolar 
staining.  These  rods  may  grow  longer  and  appear 
in  pairs  or  short  chains.  They  are  killed  by  60°  C. 
or  142°  F.  in  ten  minutes,  or  by  boiling  water  in  two 
minutes.  They  resist  drying  for  two  or  three  days 
under  natural  conditions,  but  when  drying  is  hastened 
by  artificial  means,  they  live  only  a  few  hours.  They 
resist  cold  and  freezing  for  a  long  time,  perhaps  a 
month.  Sunlight  destroys  them  in  five  hours.  In 
pus  or  sputum  they  may  live  a  few  weeks,  but  in 
cadavers  they  have  been  found  after  several  months. 
Chemicals  kill  them  as  follows:  5  per  cent,  carbolic 
acid  and  1  to  1000  bichloride  in  ten  minutes.  Animals 
are  usually  susceptible  to  Bacillus  pestis,  particularly 
guinea-pigs  and  rats,  and  it  is  said  that  simple  rubbing 
of  them  on  the  skin  of  these  beasts  will  produce  the 
infection.  It  is  similar  to  the  human  disease. 

Plague  Serum. — The  poison  of  Bacillus  pestis  is 
largely  intracellular.  It  has  been  possible,  however, 


PLATE  IV 


Bacillus  of  Bubonic  Plague.     (Abbott.) 

A,  in  pus  from  suppurating  bubo;    B,  the  bacillus  very  much 
enlarged  to  show  peculiar  polar  staining. 


SPIRILLUM  CHOLERA  ASIATICS  125 

to  get  a  serum  which  will  destroy  the  bacteria  and  can 
be  used  therapeutically.  The  bacteria  grown  in  the 
laboratory  are  killed  by  moderate  heat  and  injected 
into  animals.  The  injections  are  continued  until 
very  large  doses,  fatal  to  unprepared  animals,  are 
withstood.  The  serum  now  has  properties  which  will 
neutralize  the  endotoxins  of  the  plague  bacillus,  and 
is  called  a  bactericidal  serum.  It  is  said  to  have  also 
some  antitoxic  properties  that  neutralize  the  small 
amount  of  extracellular  poison  of  this  organism.  This 
serum  is  used  for  treatment  during  the  attack  or  for 
immunizing  those  exposed.  The  results  have  been 
promising. 

Not  only  is  this  passive  immunity  made  use  of,  but 
for  prevention  of  infection,  plague  bacilli  whose  patho- 
genic properties  are  destroyed  by  heat  are  also  injected 
precisely  as  has  been  described  for  typhoid  fever.  This 
"vaccine"  treatment  of  Haffkine,  and  one  of  the  first 
of  such  procedures,  gives  an  immunity  for  a  few  months. 
Immunity  against  a  subsequent  attack  always  follows 
plague.  Thus  there  is  an  active  immunizing  therapy 
for  plague,  and  passive  immunizing  substances  can 
be  added  to  the  patient's  own  defenses. 

SPIRILLUM  CHOLERA  ASIATICS 

Cholera  is  an  acute  inflammatory  disease  of  the  small 
intestines  characterized  by  profuse  watery  stools,  a 
profound  prostration,  muscular  pains,  and  high  fever. 
It  is  caused  by  the  Spirillum  cholera  asiaticce  or 
cholera  spirillum  or  vibrio.  The  bacteria  enter  the 
body  only  through  the  mouth,  and  settle  upon  the 


126      THE  ACUTE  SELF-LIMITED  INFECTIONS 

mucous  membrane  of  the  lower  part  of  the  small 
intestine.  This  they  penetrate  only  as  far  as  the 
deeper  layers  of  the  innermost  coat  of  the  tube,  and 
by  their  growth  cause  a  shedding  of  the  coat.  The 
shreds  of  the  desquamated  mucous  membrane  pass  off 
with  the  watery  discharges,  and  cause  the  characteristic 
"rice  water"  stools.  The  bared  and  congested  surface 
permits  absorption  of  the  poisons  of  the  spirillum,  the 
body  of  which  does  not  itself  enter  the  blood  stream. 
The  poison  quite  frequently  has  a  depressing  action 
upon  the  heart  muscle.  It  is  not  quite  certain  whether 
or  not  this  is  a  wholly  extracellular  toxin  or  combined 
closely  with  the  bacterial  bodies.  It  is  probably  mostly 
of  the  latter  character,  an  endotoxin  separated  upon 
the  disintegration  of  the  germ  cells. 

Cholera  is  a  disease  transmitted  almost  exclusively 
by  polluted  water,  although  food  infected  with  bacteria 
may,  of  course,  transmit  it.  Water  is  contaminated  by 
dejecta  of  cholera  patients,  and  the  vibrio  leaves  the 
patient  in  no  way  but  with  feces  (or  vomiting  of  intes- 
tinal contents,  a  rare  occurrence).  Large  numbers  of 
vibrios  are  present  in  the  feces  early  in  the  attack.  Later 
they  rapidly  decrease,  but  do  not  disappear  from  the 
gut  and  feces,  and  may  continue  to  come  away  in  small 
numbers  for  many  months.  In  such  cases  they  natur- 
ally pollute  anything  with  which  the  dejecta  come  in 
contact.  They  do  not  live  long  in  nature,  however,  and 
regulations  can  be  made  to  kill  them.  Flies  having 
soiled  themselves  upon  cholera  excreta  may  carry  the 
germs.  Vegetables  may  be  soiled  from  water.  Personal 
contact  and  handling  of  clothes  from  patients  have  the 
same  value  in  transmission  of  cholera  as  for  typhoid 


SPIRILLUM  CHOLERA  ASIATICS  127 

fever.  As  the  organisms  leave  the  body  only  with  the 
feces,  measures  should  be  taken  to  disinfect  them,  and 
anything  likely  to  be  soiled  with  them.  The  feces 
should  be  received  into  5  per  cent,  carbolic  acid 
solution.  The  buttocks  and  anus  should  be  wiped 
with  1  to  1000  bichloride  solution.  Clothes  or  bedding, 
glasses,  utensils,  and  other  objects  should  be  soaked 
in  these  solutions.  Boiling  when  possible  is  advisable. 
A  disinfecting  hand  lotion  should  be  constantly  used 
by  the  attendants.  It  is  necessary  to  continue  disin- 
fection of  stools  for  varying  periods  after  an  attack, 
since  bacteria  lurk  in  the  depths  of  the  intestinal 
mucosa,  and  are  excreted  long  after  the  acute  symp- 
toms have  disappeared. 

Cholera  is  diagnosticated  bacteriologically  by  culti- 
vation of  the  stools.  The  organisms  are  present  in 
almost  pure  culture,  and  can  be  made  to  grow  quite 
easily.  There  are  several  other  spirilla  of  similar  form 
and  manner  of  growth,  and  sometimes  delicate  bio- 
logical tests  (see  below)  are  necessary.  Agglutination 
tests  may  be  used  in  this  disease,  as  some  clumping 
power  is  acquired  by  the  blood  during  an  attack. 
Another  antibody  is  formed  which  has  the  power  of 
dissolving  the  cholera  spirilla.  This  is  a  bacteriolysin. 
Animals  injected  with  the  cholera  organisms  also 
acquire  this  power.  If  a  guinea-pig  be  injected  with 
spirilla  up  to  a  point  where  it  will  resist  large  numbers, 
its  blood  serum  will  dissolve  the  living  organisms 
either  in  the  test-tube  or,  what  is  better,  within  the 
abdominal  cavity  of  another  guinea-pig.  In  the  latter 
case  the  antiserum  from  the  prepared  guinea-pig  and 
living  rods  are  injected  together.  The  rods  are  devital- 


128      THE  ACUTE  SELF-LIMITED  INFECTIONS 

ized  and  the  pig  lives,  although  another  animal  receiving 
the  organisms  in  like  quantity,  but  without  serum,  will 
die.  This  is  the  method  suggested  which  can  be  used 
to  identify  suspected  cultures,  using  as  the  protective 
blood  serum  that  from  an  animal  previously  treated 
with  known  cholera  germs. 

The  cholera  spirillum  is  a  curved  organism  something 
the  shape  of  a  comma,  and  is  sometimes  called  the 
comma  bacillus.  One  end  is  apt  to  be  thicker  than 
the  other.  It  sometimes  appears  like  an  S  when  two 
are  joined  on  end.  Long  filaments  may  be  seen  in 
fluids.  In  old  laboratory  cultures  it  may  appear  as  a 
short,  straight  rod  or  club.  It  is  actively  motile  by 
means  of  a  long  single  flagellum  on  the  end.  No  spores 
are  formed.  It  measures  from  inAnr  to  yjnnr  mcn  m 
length  by  TSTIJT  mcn  m  width.  It  is  not  easy  to  measure 
since  spirilla  are  not  simple  curves  but  spirals.  It  does 
not  stain  with  great  ease,  but  a  weak  watery  solution 
of  fuchsin  is  the  best.  It  grows  best  in  the  presence  of 
oxygen  at  37.5°  C.  or  98°  F.,  but  may  grow  at  ordinary 
temperatures.  It  has  the  power  of  digesting  gelatin 
and  solidified  blood  serum,  but  does  not  clot  milk.  It 
resists  60°  C.  or  142°  F.  for  one  hour,  but  boiling  kills 
at  once.  It  multiplies  at  the  temperature  of  foodstuffs, 
and  freezing  does  not  destroy  it  under  three  days. 
Drying  kills  certainly  in  twenty-four  hours  in  diffuse 
light.  Sunlight  kills  within  one  hour.  The  figures 
indicate  some  resistance  to  heat  and  light,  but  against 
chemicals  this  is  not  maintained;  1  to  1000  bichloride 
is  fatal  in  ten  minutes;  1  per  cent,  carbolic  acid  a 
little  longer;  lime  in  any  form  is  rapidly  fatal  to  the 
spirillum. 


BACILLUS  DYSENTERIC  129 

Animals  do  not  contract  cholera  either  spontaneously 
or  artificially,  but  they  may  be  killed  by  the  germs  or 
their  poisons.  The  active  acquired  immunity  they  get 
by  repeated  injections  has  been  described.  It  has  not 
been  found  practical  to  obtain  any  serum  from  animals 
which  can  be  injected  into  human  beings  as  a  treat- 
ment. Dead  spirilla,  however,  can  be  injected  into 
well  persons  as  a  protective  measure,  precisely  as  is 
done  for  typhoid  and  plague,  and  with  good  results. 

FIG.  37 


Spirillum  of  Asiatic  cholera:    /,  stained  by  ordinary  method;  //,  stained 
to  show  flagella.     (Abbott.) 


BACILLUS  DYSENTERIC 

Dysentery  occurs  in  two  forms — the  bacillary  type 

and  the  amebic  type.    The  former  is  caused  by  bacteria, 

while  the  latter  is  a  protozoon  disease   (see  Chapter 

XIV).      Bacillary   dysentery   is   an   acute    infectious 

9 


130     THE  ACUTE  SELF-LIMITED  INFECTIONS 

disease,  its  chief  lesion  being  a  violent  inflammation 
of  the  lining  of  the  large  intestines.  The  disease  is 
caused  by  the  Bacillus  dysenteries  or  dysentery  bacillus. 
It  is,  however,  better  to  say  that  a  group  of  organisms 
under  this  name  gives  rise  to  it  because  there  are  many 
varieties  with  different  chemical  and  serum  reactions, 
producing  attacks  of  varying  severity.  Their  general 
pathogenic  and  etiological  effects  may  be  discussed 
together,  however. 

In  cholera  the  chief  lesions  are  in  the  lower  small 
intestine,  but  otherwise  the  two  diseases  have  many 
things  in  common. 

The  bacilli  enter  probably  only  by  the  mouth  in 
infected  food  and  drink,  and  pass  through  the  ali- 
mentary tract  to  their  organ  of  predilection,  the 
colon.  Here  they  penetrate  the  mucous  lining  to  its 
deeper  layers,  causing  violent  irritation.  They  may 
get  deeper  into  the  wall  or  even  to  the  glands  draining 
the  colon,  but  not  into  the  blood.  The  inflammation 
gives  rise  to  diarrhea  which  passes 'from  feculent  to 
mucous,  to  bloody  mucous,  and  may  be«  almost  wholly 
blood.  These  effects  are  due  to  the  effort  of  the 
colonic  wall  to  rid  itself  of  the  poisons,  and  the  body 
seems  to  choose  this  method  to  free  itself  of  the 
intruder.  This  fact  is  further  shown  when  we  inject 
susceptible  small  animals  with  the  poisons,  for  a  con- 
gestion of  the  colon  with  diarrhea  results,  although  no 
living  organisms  are  present.  The  poisons  of  the  dysen- 
tery bacilli  are  probably  both  extracellular  and  endo- 
toxins,  the  latter  being  more  abundant.  The  toxic 
effect,  therefore  is  exerted  by  the  existence  of  the 
germs  in  the  mucous  membrane  giving  off  poisonous 


BACILLUS  DYSENTERIC  131 

products  of  their  life,  and  to  a  greater  degree,  by  the 
poisons  liberated  upon  their  disintegration.  The 
poisons  are  absorbed  into  the  blood,  giving  rise  to  an 
irregular  fever  in  which  sudden  drops  are  common. 
This  sudden  fall  of  temperature  may  be  observed  in 
animals  receiving  doses  of  the  poison. 

Dysentery  is  transmitted  like  other  diarrheal  dis- 
orders, that  is,  by  the  pollution  of  food  and  drink  by 
discharges  of  patients,  since  the  germs  leave  the  body 


,     < 


FIG.  38 


«^>%    *  % 


f  -^ 

Dysentery  bacilli.     X  1000  diameters.     (Park.) 

only  by  the  feces.  Disinfection  of  excreta,  clothes, 
utensils,  and  hands  should  be  done  as  for  cholera. 
After  an  attack  persons  may  be  carriers,  and  disinfec- 
tion of  stools  should  not  cease  upon  clinical  recovery. 

The  blood  acquires  some  resistance  to  dysentery 
bacilli  during  an  attack,  comparable  closely  to  the 
changes  in  cholera ;  that  is  bacterioly tic  substances  and 
agglutinins  are  to  be  found.  Advantage  of  this  is  taken 


132      THE  ACUTE  SELF-LIMITED  INFECTIONS 

in  immunizing  the  lower  animals  with  toxins  obtained 
in  laboratory  cultures.  As  an  aid  in  the  diagnosis  of 
dysentery  the  stools  in  which  the  bacteria  may  be  found 
almost  in  pure  culture  are  cultivated.  The  shreds  of 
membrane  or  mucus  from  the  stools  are  selected. 
The  development  in  the  laboratory  is  comparatively 
simple,  but  to  identify  the  species  or  variety  is  any- 
thing but  easy.  The  agglutinins  in  the  patient's 
blood  may  be  tested  against  pure  laboratory  cultures 
of  known  varieties,  and  thus  a  bacteriological  diagnosis 
as  to  the  type  may  be  made.  Thus  for  diagnosticating 
dysentery  we  have  only  the  feces  culture  and  agglutin- 
ation test.  Since  the  bacilli  are  not  in  the  blood, 
cultures  of  this  are  not  made. 

The  dysentery  bacillus  is  a  short,  straight,  probably 
non-motile  rod  with  rounded  ends.  It  is  quite  like 
the  typhoid  bacillus  in  shape  and  size,  but  unlike  this 
germ  does  not  move  actively.  It  may  at  times  show 
degenerated  forms.  It  is  usually  single,  but  may  be 
in  pairs.  It  stains  easily.  It  grows  both  aerobically 
and  anaerobically,  but  better  under  the  former  con- 
ditions. Its  growth  upon  laboratory  media  is  also 
like  that  of  the  typhoid  bacillus.  Best  development 
occurs  at  37°  C.  or  98°  F.,  and  death  results  when  60°  C. 
or  142°  F.  is  held  for  ten  minutes. 

It  resists  freezing  for  a  long  time,  possibly  some 
weeks.  It  is  killed  by  drying  only  after  long  periods. 
Its  resistance  to  chemicals  is  practically  the  same 
as  that  of  typhoid  bacilli.  Animals  do  not  contract 
dysentery  when  they  take  the  bacilli  by  mouth,  but 
when  germs  or  their  toxins  are  introduced  under  the 
skin,  into  the  vein  or  peritoneum,  profound  intoxica- 


VINCENT'S  ANGINA  133 

tion  occurs,  with  fall  of  temperature,  peritonitis,  diar- 
rhea, and  in  some  cases  hemorrhage  in  organs  or  body 
cavities. 

Dysentery  Antiserum. — Nevertheless,  animals,  notably 
rabbits  and  horses,  have  been  made  to  withstand 
large  doses  by  preparation  with  graded  amounts. 
They  develop  sera  containing  anti-substances  to  both 
the  endo-  and  extracellular  dysentery  toxins.  This 
serum  has  been  used  therapeutically  in  the  treatment 
of  dysentery.  Thus  passive  immunity  can  be  secured, 
but  so  far  no  great  success  has  met  attempts  to  raise 
the  resistance  of  human  beings  to  dysentery  by 
injecting  dead  or  attenuated  bacilli;  no  active  immunity 
has  been  achieved.  It  may  be  well  to  add  that  in 
producing  the  serum  from  animals  to  inject  into 
human  beings,  several  varieties  of  the  bacillus  are 
used,  since  dysentery  may  be  caused  by  several 
varieties.  Thus  an  antiserum  potent  against  more 
than  one  type  of  infection  is  obtained,  a  so-called 
polyvalent  antiserum. 

VINCENT'S  ANGINA 

Vincent's  angina  is  a  very  important  inflammatory 
disease  of  the  tonsils  and  pharynx,  sometimes  simu- 
lating diphtheria  in  that  a  false  membrane  is  also 
characteristic  of  the  disease.  The  causative  bacteria 
are  spirilla  and  fusiform  rods,  probably  two  stages  of 
development  of  the  same  organism,  since  it  is  believed 
that  the  former  develop  from  the  latter.  The  earlier 
stage  is  the  time  when  the  pseudomembrane  appears, 
but  this  soon  gives  place  to  punched-out  ulcerations. 


134     THE  ACUTE  SELF-LIMITED  INFECTIONS 

The  disease  is  mild,  producing  only  a  little  local  pain, 
slight  fever,  and  malaise.  The  disease  may  coexist 
with  diphtheria,  aggravating  the  latter.  The  bacteria 
gain  admission  by  direct  transfer  from  a  patient  to 
the  unaffected  throat.  The  condition  is  not  very 
contagious.  Disinfection  should  be  observed  by 
frequent  cleansing  of  throat  and  mouth  by  mild  anti- 

FIG.  39 


Vincent's  bacillus  with  accompanying  spirochsetse.       (Park. 

septics.  Rinse  water  and  cloths  used  to  wipe  the 
mouth  may  be  rendered  innocuous  by  any  practical 
disinfectant  working  for  half  an  hour.  Little  is  known 
of  the  method  of  action  of  the  bacteria.  They  probably 
produce  the  condition  by  soluble  poisons.  In  diag- 
nosticating Vincent's  angina  a  smear  from  the  false 
membrane  stained  with  particular  care  will  show 
long  fusiform  rods  with  sharp  ends  taking  the  dye 


CONJUNCTIVITIS  135 

more  deeply  at  the  ends  and  in  the  form  of  transverse 
bands,  and  quite  long  wavy  spiral  organisms,  usually 
having  shallow,  irregular  curvatures.  The  bacilli  are 
4  oVo  to  2"oVo  inch  long  and  47  Jo  o"  to  -sifiro  o"  inch  wide. 
They  probably  grow  best  under  anaerobic  conditions. 
There  is  no  specific  treatment. 

CONJUNCTIVITIS 

There  are  many  bacteria  capable  of  producing  inflam- 
mations of  the  conjunctival  sac,  but  there  are  a  few 
that  seem  peculiar  in  being  found  only  in  this  place. 
Whether  they  are  separate  species  or  not  remains  to 
be  seen.  The  most  important  mild  inflammation  of 
the  conjunctiva  is  the  "pink  eye."  This  acute  con- 
dition is  transmitted  by  direct  or  indirect  passage  of 
moist  infective  material  from  one  patient  to  another. 
Therefore  an  affected  eye  should  be  kept  covered  and 
dressings  handled  carefully.  The  organisms  are  killed 
by  very  weak  solutions  of  the  ordinary  disinfectants, 
and,  indeed,  probably  do  not  resist  boric  acid  very  long. 
The  causative  germ  is  the  Koch-Weeks  bacillus  of 
conjunctivitis.  It  is  similar  in  size,  shape,  and  staining 
properties  to  the  influenza  bacillus,  but  differs  from  it 
in  that  it  will  grow  in  the  absence  of  hemoglobin,  and 
with  reasonable  ease  on  ordinary  culture  media.  It 
is  destroyed  at  60°  C.  or  142°  F.'  in  two  minutes.  It 
does  not  affect  animals.  There  is  no  specific  therapy. 

Another  form  of  conjunctivitis  chiefly  affecting  the 
angles  of  both  eyes  and  running  a  subacute  course  is 
caused  by  the  bacillus  of  Morax  and  Axenfeld.  These 
organisms  as  seen  in  smears  made  best  from  exudate 


136      THE  ACUTE  SELF-LIMITED  INFECTIONS 

collecting  over  night,  appear  as  short  end-to-end  ovoid 
rods,  each  about  TSTTHF  inch.  long.  They  may  be 
cultivated  at  body  temperature  on  media  containing 
blood  or  blood  serum.  They  produce  disease  by  their 
presence  and  by  some  form  of  toxin  little  understood. 
The  disease  does  not  affect  animals. 

FIG.  40 


Koch-Weeks  bacillus  (pink-eye),  3d  generation.      X  1000  diameters 
(Weeks.) 


PERTUSSIS  OR  WHOOPING  COUGH 

Many  different  organisms  have  been  held  responsible 
for  this  disease.  The  one  now  holding  the  field  was 
described  by  Bordet  and  Gengou  several  years  ago, 
but  only  cultivated  artificially  within  the  last  few 
years.  Although  the  discoverers  failed  to  produce  the 
disease  in  monkeys  when  using  this  bacillus,  never- 
theless they  hold  that  the  presence  of  agglutinins  and 
a  refined  blood  reaction,  called  complement  deviation, 
in  the  blood  of  patients  are  sufficient  to  incriminate  it 


BACILLUS  MELITENSIS  137 

as  the  cause  of  whooping  cough.  They  assert  that  endo- 
toxins  are  formed.  The  disease  is  transferred  directly 
from  one  patient  to  another  by  means  of  spray 
from  coughing,  spitting,  or  talking.  The  rod  grows 
only  at  body  temperature  in  the  presence  of  blood  or 
its  coloring  matter.  It  is  very  like  the  Bacillus  influ- 
enza in  size  and  shape.  It  is  found  in  the  sputum 
early  in  the  disease  as  a  small  ovoid  polar  staining  rod, 
arranged  in  pairs  end  to  end.  It  is  stained  easily. 
It  does  not  produce  the  disease  in  animals.  Sputum 
should  be  received  in  5  per  cent,  carbolic  acid,  and 
cloths  used  to  wipe  the  mouth  should  be  soaked  in 
the  same  solution. 

BACILLUS  MELITENSIS 

Malta  fever  is  an  acute  infectious  disease,  endemic 
along  the  Mediterranean,  following  a  course  similar 
to  typhoid  fever,  but  usually  of  less  serious  nature.  It 
is  caused  by  the  Bacillus  melitensis.  Goats  harbor  the 
organisms  and  pass  them  out  through  the  milk,  an 
important  food  in  Malta.  Persons  can  be  infected  by 
introduction  through  a  wound.  The  disease  is  a  septi- 
cemia  and  endotoxins  are  probably  set  free.  It  is 
probably  not  transmitted  from  man  to  man.  The 
diagnosis  is  made  by  means  of  blood  cultures  or  by 
the  agglutination  test.  The  bacilli  are  exceedingly 
short,  almost  coccus  shape.  They  are  about  TSTOT 
inch  long,  single  or  in  pairs.  No  motility  is  seen,  and 
no  spores  are  formed.  They  stain  easily  and  grow  well 
in  ordinary  media  at  37°  C.  or  98°  F.  Monkeys  are 
the  only  animals  infectable.  Vaccines  of  dead  cultures 
may  be  used.  The  bacilli  are  killed  by  the  same 
methods  as  the  typhoid  bacillus. 


CHAPTER    X 
THE  MORE  CHRONIC  INFECTIOUS  DISEASES 

THE  diseases  which  have  been  discussed  are  the 
most  important  acute  infectious  diseases,  and  now 
those  which  are  accustomed  to  follow  a  more  prolonged 
course  must  be  considered.  It  should  be  emphasized, 
however,  that  any  one  of  these  may  assume  a  rapid 
or  fulminating  character  and  run  its  course  quite  as 
rapidly  as  the  acute  infections.  These  chronic  infec- 
tions, particularly  tuberculosis  and  syphilis,  are  perhaps 
the  most  widespread  of  diseases. 

BACTERIUM  TUBERCULOSIS 

Tuberculosis  is  an  infectious  disease  capable  of 
attacking  any  organ  or  structure  in  the  body,  although 
its  commonest  site  is  the  lung.  The  organism  is  the 
Bacterium  tuberculosis  or  tubercle  bacillus.  The  organ- 
ism enters  the  body  chiefly  through  the  mouth  and 
nose,  usually  by  the  air,  but  also  in  food  and  drink. 
If  it  follow  the  air  passages  it  may  settle  upon  the 
nasal,  buccal,  pharyngeal,  laryngeal,  or  bronchial 
mucous  membranes.  These  it  penetrates,  and  settles 
usually  where  there  is  lymph  tissue.  This  it  follows 
with  the  lymph  flow,  and  finds  lodgement  at  some  point 
of  low  resistance.  It  may  penetrate  to  the  true  lung 
tissue  with  the  air  current,  but  it  probably  settles  in 


BACTERIUM  TUBERCULOSIS  139 

some  of  the  smaller  air  tubes,  and  extends  into  adjoin- 
ing lung  tissue  by  continuity.  It  may  get  into  the 
lungs  by  following  the  lymph  way,  or  as  has  lately 
been  proven,  it  may  get  there  from  the  blood  stream  or 
lymph  when  it  has  been  taken  into  the  intestines  in  food 
or  drink.  These  bacteria  can  pass  through  a  mucous 
membrane  into  the  deeper  tissue  without  leaving  any 
inflammation  at  their  point  of  entry.  After  having 
entered  the  tissues  proper  they  may  be  carried  any- 
where by  the  lymph  and  probably  by  the  blood. 

Tubercles. — Having  settled  at  a  point  of  low  resist- 
ance, they  irritate  the  tissue  rather  slowly  to  produce  a 
localized  inflammation  which  is  called  a  tubercle.  This 
is  usually  a  gray  body  about  the  size  of  a  millet  seed. 
The  cells  composing  this  little  mass  are  very  much 
the  same  as  those  seen  in  chronic  local  non-tuberculous 
inflammations,  but  their  arrangement,  particularly 
when  combined  with  large  cells  having  numerous 
nuclei  about  their  edge  (giant  cells),  is  rather  character- 
istic of  the  disease.  Many  of  these  tubercles  spread 
centrifugally  and  coalesce.  The  centre  of  the  tubercles, 
being  devoid  of  nutriment,  since  the  blood  supply  is 
cut  off,  undergoes  cheese-like  or  caseous  softening. 
The  combination  of  many  tubercles  and  their  destroyed 
centre  produces  large  caseous  abscesses.  When  these 
are  in  the  lungs  the  softened  centres  may  be  removed 
by  being  coughed  up  after  the  process  has  ulcerated 
into  an  air  passage.  In  the  kidney  the  same  general 
thing  may  occur,  and  the  softened  matter  goes  into 
the  urine. 

Forms  of  Tuberculosis. — When  the  process  ulcerates 
into  the  blood  supply  there  may  result  a  rapid  dissemi- 


140      THE  MORE  CHRONIC  INFECTIOUS  DISEASES 

nation  of  the  bacteria  throughout  the  body,  wTith 
the  production  of  innumerable  miliary  tubercles  every- 
where. Among  the  special  forms  of  tuberculosis  are 
meningitis,  hip  disease,  or  spine  disease.  The  first  is 
a  long-standing  inflammation  in  which  the  coverings 

FIG.  41 


Tuberculosis  of  the  lung.     (Stengel.) 

of  the  brain  and  cord  and  the  superficial  layers  of 
these  organs  are  involved  in  an  extensive  inflammation. 
The  hip  and  spine  diseases  arise  when  the  bacteria  get 
into  the  soft  marrow  of  the  bones,  and  extend  to  the 
joint  and  tissues  about  it. 


BACTERIUM  TUBERCULOSIS  141 

Toxins. — The  peculiar  evidences  of  tuberculosis  are 
due  to  the  toxins  elaborated  by  the  causative  germ, 
which  are  both  extracellular  and  endotoxic.  The  former 
produce  the  constitutional  symptoms  of  fever  and 
general  depression  of  health.  They  are  also  probably 
responsible  for  some  of  the  inflammation  in  the  neigh- 
borhood of  tubercles.  The  endotoxins,  on  the  other 
hand,  produce  the  peculiar  local  inflammation  called 
the  tubercle,  and  cause  its  degeneration  into  caseous 
material.  During  an  infection  with  tuberculosis  there 
will  be  developed  in  the  body  fluids  a  very  slight 
amount  of  substance  as  antibody  to  these  endo-  and 
extracellular  poisons.  It  is  of  little  importance  in 
the  diagnosis,  treatment,  or  protection  of  the  indi- 
vidual, and  a  specific  resistance  to  tuberculosis  is  not 
acquired  by  passing  through  an  attack,  although  it 
is  said  that  a  tuberculous  person  cannot  be  reinfected 
with  tuberculosis.  Recovery  ensues  when  the  health  of 
the  individual  and  his  tissues  is  strong  enough  to 
inhibit  the  multiplication  of  bacilli. 

Predisposing  Causes  and  Transmission. — A  lighting 
up  of  the  disease  may  occur  when  the  resistance 
weakens  by  reason  of  some  acute  disease,  bad  habits, 
and  the  like.  Tuberculosis  spares  no  walk  of  life,  but 
is  more  common  where  the  lack  of  body  care  reduces 
resistance.  It  is  preeminently  the  disease  of  crowded, 
dark,  illy  ventilated,  badly  drained  tenements.  It  comes 
in  the  pulmonary  form  frequently,  as  an  infection 
on  top  of  an  acute  cold.  The  disease  is  spread  in  by 
far  the  largest  percentage  of  cases  by  the  direct  inhala- 
tion of  germs  coughed  out  by  a  tuberculous  person 
and  contained  in  dust  contaminated  by  tuberculous 


142     THE  MORE  CHRONIC  INFECTIOUS  DISEASES 

sputum.  The  sputum  must,  of  course,  dry  before  it 
is  pulverized  into  dust  by  walking  on  it  or  sweeping 
it.  The  dust  arising  from  soiled  handkerchiefs  or 
cloths  is  likewise  a  danger.  Park  says  that  as  many  as 
5,000,000,000  tubercle  bacilli  may  be  expectorated  by 
a  consumptive  person  in  twenty-four  hours.  Since  the 
ordinary  uneducated  consumptive  is  very  careless  of 
his  expectoration,  the  danger  is  obvious.  The  great 
movement  against  the  "white  plague"  now  active 
throughout  the  world  is  rapidly  correcting  the  habits 
of  careless  patients. 

Tuberculosis  may  also  be  transmitted  by  the  infec- 
tion of  food  in  the  soiled  hands  of  patients,  or  flies 
may  feed  upon  sputum  and  carry  the  germs  upon 
their  body.  The  study  of  the  transmission  of  tuber- 
culosis from  the  cow  to  the  human  being  has  now 
progressed  to  a  point  near  solution.  Koch  said  that 
the  bovine  form  of  tuberculosis  is  not  contracted  by 
the  human  being.  This  is  true  for  tuberculosis  of  the 
lungs,  but  children  are  susceptible  to  the  bovine  form, 
and  it  affects  them  in  the  glands  of  the  neck  and  of 
the  abdominal  cavity.  Cows  may  give  off  tubercle 
bacilli  in  their  milk  even  when  there  is  very  slight 
evidence  of  the  disease  in  their  body. 

The  tubercle  bacillus  may  be  eliminated  from  the 
human  body  by  the  feces,  and  health  authorities  are 
requiring  the  disinfection  of  sewage  from  sanatoria. 
Tuberculosis  is  very  rarely  hereditary,  but  children  born 
of  tuberculous  parents  are  not  quite  as  robust  as  chil- 
dren born  of  non-tuberculous  persons,  and  therefore 
they  more  easily  contract  the  disease  from  the  sur- 
roundings contaminated  by  ill  parents. 


BACTERIUM   TUBERCULOSIS  143 

Disinfection. — To  disinfect  material  from  the  tubercu- 
lous individual  it  is  necessary  to  collect  it  in  some 
manner,  permitting  burning  or  the  action  of  chemicals 
over  a  long  time.  Tuberculous  sputum  is  best  received 
in  cardboard  boxes  inclosed  in  a  tin  cup.  The  boxes 
are  burned,  and  the  tin  cup  washed  in  5  per  cent,  car- 
bolic acid  at  frequent  intervals.  If  the  person  expec- 
torate into  cloths  they  should  be  burned  or  soaked  in 
5  per  cent,  carbolic  for  at  least  six  hours.  If  neither 
of  these  methods  is  used  expectoration  should  be 
received  in  a  bowl  or  pot  containing  5  per  cent,  carbolic 
acid.  Feces  and  urine  should  be  received  and  well  mixed 
into  the  same  solution.  Milk,  unless  it  is  known  to 
come  from  a  non-tuberculous  cow,  should  not  be  used. 
After  death  from  tuberculosis  the  room  and  all  con- 
tents should  be  disinfected  with  formaldehyde  gas. 

Diagnosis. — The  most  important  means  of  diag- 
nosis is  by  finding  the  tubercle  bacillus.  To  do 
this,  the  sputum,  urine,  feces,  pus,  exudate,  or  a 
piece  of  tissue  is  taken,  stained  by  special  methods, 
or  injected  into  guinea-pigs.  The  method  employed 
for  staining  these  bacteria  consists  in  using  a  dye 
having  an  affinity  for  the  peculiar  waxy  character  of 
the  germ  and  not  easily  removed  by  acids  after  it  has 
once  penetrated  it.  The  bacteria  are  called  acid-fast 
for  this  reason.  The  stain  consists  of  carbolic  acid 
and  fuchsin.  The  former  helps  the  latter  to  penetrate 
the  germ.  We  make  smears  upon  slides,  stain  them 
by  this  solution,  treat  them  with  an  acid  which  will 
decolorize  everything  but  the  tubercle  bacillus.  This 
will  show  us  red  bacilli. 

Sometimes  the  germs  are  present,  but  cannot  be 


144     THE  MORE  CHRONIC  INFECTIOUS  DISEASES 

found  by  staining.  Some  of  the  material  is  then 
introduced  under  the  skin  or  into  the  peritoneal 
cavity  of  guinea-pigs.  If  tubercle  bacilli  be  present, 
evidences  of  the  disease  will  appear  in  these  animals 
in  from  two  to  five  weeks.  The  bacilli  can  be  found  by 
staining  smears  from  the  tubercles.  Agglutinins  are 
formed  in  tuberculosis,  but  the  clumping  test  is  of 
little  value. 

The  tuberculin  reaction  is  a  very  important  diag- 
nostic measure.  During  its  growth  on  artificial  media 
in  the  laboratory,  the  tubercle  bacillus  develops  its 
endo-  and  extra-cellular  toxins.  If  these  poisons, 
called  "tuberculin,"  obtained  by  removing  the  living 
organisms  from  a  fluid  culture,  be  injected  under  or 
rubbed  into  the  skin,  a  characteristic  reaction  occurs. 
The  subcutaneous  injection  of  as  small  a  quantity  as 
5  milligrams  or  about  yV  minim  of  Koch's  tuberculin 
will  cause  a  definite  rise  of  temperature  and  a  feeling 
of  general  malaise  within  twenty-four  hours.  The 
inunction  of  a  drop  of  this  solution  into  the  skin,  com- 
bined with  a  slight  irritation  of  the  surface,  will  cause 
a  reddened  papule  or  even  a  vesicle  upon  a  swollen 
base  to  appear  within  twenty-four  hours.  There  are 
several  modifications  of  this  skin  test  in  practice,  but 
the  principle  is  the  same  in  all.  It  is  claimed  by  many 
that  all  adults  have  some  tuberculosis  in  their  body, 
acquired  during  childhood,  but  which  has  remained 
quiet  or  has  healed  completely.  For  this  reason  the 
skin  test  may  be  positive  in  adults  who  are  really  not 
suffering  from  their  slight  latent  infection,  and  it  is 
therefore  not  reliable.  It  should  only  be  used  in  chil- 
dren. The  supposed  cause  of  the  tuberculin  test  either 


PLATE  V 


Bacterium  Pneumoniae  in   Blood  of  Rabbit.     (Abbott.) 

Showing  encapsulated  cocci,  red  and  -white  blood  cells. 


BACTERIUM  TUBERCULOSIS  145 

under  or  upon  the  skin  is  the  stimulation  of  the  tuber- 
culous disease  by  the  introduced  toxin,  and  the  out- 
pouring from  the  tubercles  of  more  of  their  own  poison. 
No  reaction  of  any  sort  follows  the  administration  of 
tuberculin  to  persons  free  from  tuberculosis. 

Morphology  and  General  Characteristics. — The  tubercle 
bacillus  is  a  true  parasite,  that  is,  it  does  not  multiply 
in  nature  outside  the  animal  body.  It  is  a  rather 
large  organism,  about  TOTTOT  mcn  wide  and  from 
YolToir  to  5~oVo  inch  long.  It  may  be  straight  or  slightly 
bent,  usually  single,  but  also  in  pairs.  It  is  non- 
motile,  and  produces  no  spores.  It  stains  with  con- 
siderable difficulty,  owing  to  its  thick  cell  wall.  There 
is  much  fatty  and  waxy  matter  in  the  tubercle  bacillus 
which  gives  it  its  resistant  power.  It  grows  upon 
laboratory  culture  media  very  slowly.  For  this 
reason  it  must  be  obtained  in  as  pure  a  condition  as 
possible.  Cultures  are  best  made  from  the  lesions  in 
guinea-pigs.  For  its  growth  this  organism  requires 
the  addition  of  glycerin,  blood  serum,  or  egg  to  the 
ordinary  nutrient  broths  and  jellies.  It  will  grow  only 
at  body  temperature,  and  not  at  room  temperature. 

It  is  killed  by  an  exposure  to  60°  C.  or  142°  F.  in 
thirty  minutes,  to  70°  C.  or  160°  F.  in  ten  minutes, 
and  at  95°  C.  or  200°  F.  in  one  minute  in  watery 
suspension.  Dry  heat  at  100°  C.  or  212°  F.  requires 
about  one  hour.  The  organisms  resist  drying  in  the 
dark  for  considerable  periods.  Direct  sunlight  kills 
them  if  in  thin  layer  or  small  clumps,  within  four 
hours.  Diffused  light  requires  two  weeks  for  their 
destruction.  Sputum  protected  from  direct  sunlight 
may  contain  living  bacilli  possibly  for  one  year.  Five 
10 


146      THE  MORE  CHRONIC  INFECTIOUS  DISEASES 

per  cent,  carbolic  acid  should  certainly  kill  them  in 
sputum  in  twelve  hours;  in  watery  suspension  in 
thirty  minutes.  Bichloride  of  mercury  is  not  of  value 
for  sputum  disinfection,  but  in  strength  of  1  to  1000 
in  watery  suspension  is  fatal  in  one  hour.  No  kind 
of  animal  is  absolutely  resistant  to  tuberculosis,  but 
there  are  some  that  very  seldom  present  the  spon- 
taneous disease,  notably  dogs  and  horses. 

There  are  four  forms  or  varieties  of  the  tubercle 
bacillus:  the  human,  bovine  or  cow,  bird,  and  reptil- 
ian. The  first  two  only  concern  us,  and  the  distin- 
guishing features  of  these  groups  are  of  small  importance 
here.  The  infectiousness  of  the  bovine  form  for 
humans  has  been  mentioned.  The  human  form  is  of 
very  low  virulence  for  the  cow,  but  may  infect  most 
of  the  smaller  animals.  It  has  been  found  impossible 
to  obtain  from  any  of  the  lower  animals  a  serum  which 
will  have  a  beneficial  effect  upon  the  disease  in  human 
beings.  That  is,  no  serum  can  be  procured  which  will 
give  a  passive  immunity. 

Tuberculin. — The  poisons  made  in  cultures  and  used 
for  the  tuberculin  test  in  the  form  of  Koch's  tuber- 
culin have  already  been  mentioned.  There  are  many 
forms  of  tuberculin  which  are  incidentally  modelled 
after  Koch's  plans.  His  original  was  a  broth  upon 
which  the  bacteria  had  grown,  but  freed  of  living  forms 
and  reduced  by  evaporation  to  one-tenth  its  original 
volume.  This  contained  both  the  endo-  and  extra- 
cellular toxins.  His  later  forms  consisted  of  killed 
bacteria,  of  a  watery  extract  from  them,  and  lastly, 
living  bacteria  so  reduced  in  virulence  that  they  could 
not  produce  tuberculosis.  These  are  all  tuberculins, 


TREPONEMA   PALLIDUM  147 

the  last  forms  being  called  vaccines  also.  We  inject 
them  under  the  skin  of  tuberculous  patients,  beginning 
with  extremely  minute  doses,  too  small  to  produce 
the  tuberculin  reaction  described  above.  We  increase 
the  quantity  gradually  until  the  patient  can  endure 
large  amounts.  It  is  maintained  that  this  treatment 
is  very  beneficial  and  that  a  slight  immunity  is  achieved. 
Opinions  vary  as  to  its  value,  but  those  who  have  had 
longest  experience  usually  testify  to  its  efficacy.  This 
is  in  reality  an  active  immunization  during  the  course 
of  the  disease,  but  it  has  not  been  found  possible  to 
inject  a  healthy  person  in  the  same  manner  and 
thereby  increase  his  resistance  to  tuberculosis. 

TREPONEMA  PALLIDUM 

Syphilis  is  one  of  the  venereal  diseases.  It  is  chiefly 
acquired  by  cohabitation,  but  may  also  be  contracted 
by  nurses  and  physicians  in  their  professional  relations 
with  patients.  It  is  a  chronic  infectious  disease 
characterized  by  three  stages,  the  first  a  primary, 
acute,  active  self-limited  ulceration,  with  some  regional 
lymph  gland  swellings;  second,  a  period  in  which 
various  eruptions  appear  on  the  skin  and  mucous 
membranes,  with  slowly  progressive  changes  in  some 
of  the  internal  organs,  and  third,  a  last  stage  of  soft 
tumor  formation  (gumma),  with  fibrous  affections  of 
the  organs  and  degenerations  of  the  nervous  system. 

It  is  caused  by  a  spiral  organism  called  the  Spiro- 
chceta  pallida  or  Treponema  pallidum  This  bac- 
terium enters  small  cracks  or  wounds,  penetrates  to 
the  deeper  layers,  invades  the  lymph  channels,  and 


148     THE  MORE  CHRONIC  INFECTIOUS  DISEASES 

produces  the  primary  sore,  the  hard  chancre.  Even 
before  this  is  fully  developed,  the  spirochsetse  have 
journeyed  to  the  neighboring  lymph  glands  where  an 
enlargement  results.  They  then  invade  both  the  lymph 
routes  and  the  blood  and  rapidly  infest  all  bodily 
tissues.  They  stimulate  the  small  round  cells  of  blood 
and  tissue  to  multiply  even  up  to  fibrous  tissue  forma- 
tion, and  they  cause  degeneration  of  the  functionating 
structures.  Just  how  they  make  the  gumma  is  only 
conjectured.  All  their  effects,  however,  are  probably 
due  to  the  toxins  set  free  upon  their  death  and  dis- 
integration. The  spirochsetse  remain  in  the  body  as 
long  as  the  patient  lives,  if  untreated.  They  leave  the 
patient  probably  only  with  the  moisture  of  ulcerated 
surfaces,  and  one  protects  against  contamination  by 
covering  the  ulcerated  surfaces  or  wearing  hand 
protection.  The  mildest  of  antiseptics  will  destroy 
the  germs.  The  incubation  period  varies  from  four 
weeks  to  as  many  months. 

Forms  of  Syphilis. — This  frightful  disease  which 
causes  so  much  mental  and  physical  suffering  may  be 
hereditary,  congenital,  or  acquired.  The  first  and  the 
last  are  easy  to  understand.  The  congenital  form  is 
acquired  by  the  infant  at  birth  from  some  open, 
active  lesions  on  the  mother.  The  course  of  the  three 
types  varies  a  little,  but  the  ultimate  effect  is  the 
same  in  all. 

Transmission. — Aside  from  cohabitation  syphilis  may 
be  transmitted  by  kissing,  or  using  any  object  that  has 
come  in  contact  with  an  open  sore.  Wet-nurses  often 
contract  it  and  transmit  it.  In  protecting  against  infec- 
tion a  weak  1  to  2000  bichloride  of  mercurv  solution 


TREPONEMA   PALLIDUM  149 

should  always  be  on  hand  that  the  ulcers  may  be 
wiped  before  examination  and  the  hands  disinfected 
afterward.  That  sleeping  with  or  using  anything 
belonging  to  a  syphilitic  must  be  avoided  goes  with- 
out saying. 

Diagnosis. — In  the  serum  of  a  syphilitic,  and  the  say- 
ing goes,  "once  a  syphilitic,  always  so,"  certain  anti- 
bodies are  formed  that  can  be  made  use  of  in  diagnosis. 
This  is  the  basis  of  the  Wassermann  test  upon  the 
blood.  This  is  due  to  antibodies  like  bacteriolysins. 
Its  theory  and  practice  are  too  intricately  technical 
to  be  included  here.  Suffice  it  to  say  that  it  is 
certainly  a  positive  test  in  95  per  cent,  of  syphilitic 
cases.  Otherwise  syphilis  is  diagnosticated  by  finding 
the  treponema  in  the  serum  which  exudes  from  chancres, 
skin  eruptions,  and  mucous  patches,  or  the  venereal 
warts  on  mucous  membranes.  This  serum  is  taken 
and  looked  at  unstained  upon  a  background  of  India 
ink  or  by  what  is  called  dark  field  illumination,  which 
is  a  process  by  which  the  light  is  made  to  shine  upon 
the  body  of  the  spiral  from  the  side.  It  can  also  be 
stained  by  appropriate  methods,  but  its  minute  size 
and  paleness  make  this  a  trying  test. 

Morphology  and  General  Characteristics. — The  Spiro- 
cli&ia  pallida  is  a  corkscrew-like,  actively  motile, 
delicate  thread.  Its  windings  assume  the  form  of  a 
large  arc  of  a  small  circle,  and  vary  from  four  to 
twenty.  It  is  yinnmr  to  y sir oo"  mcn  wide  and  from 
-g-oVo-  to  TTOTF  inch  l°ng-  It  moves  by  end  flagella, 
in  a  screwing  and  waving  motion.  It  is  killed  rapidly 
by  drying,  a  very  fortunate  thing,  as  many  people 
are  thereby  protected.  Against  weak  bichloride  and 


150     THE  MORE  CHRONIC  INFECTIOUS   DISEASES 

carbolic  acid  it  has  no  resistance.  Alcohol  will  destroy 
it  in  five  minutes.  Up  until  the  beginning  of  1911  no 
success  had  met  attempts  to  cultivate  these  spirals 
in  the  laboratory.  Noguchi  finally  succeeded  in 
growing  them  under  anaerobic  conditions  in  a  mixture 
of  serum  and  agar  to  which  a  piece  of  sterile  liver  or 

FIG.  42 


Treponema  pallidum  appearing  as  bright  refractive  body  on  a  dark   field, 
as  shown  by  India  ink  or  ultramicroscope.    (Park.) 


kidney  of  rabbit  had  been  added.  Only  rabbits  and 
monkeys  among  the  lower  animals  can  be  made  to 
contract  syphilis,  but  of  these  only  the  latter  shows 
any  similarity  to  man  in  the  course  of  the  disease. 
When  infective  crusts  from  eruptions  or  serum  exuding 
from  them  is  kept  in  the  test-tube  for  six  hours, 
infection  can  no  longer  be  transferred  to  monkeys. 


BACTERIUM  LEPRM  151 

No  serum  of  therapeutic  value  has  as  yet  been  pro- 
duced, nor  can  immunity  be  induced  by  injecting 
dead  spirochetes.  Lately  Noguchi  has  made  an  extract 
of  spirochaete  bodies  which  can  be  used  as  a  skin  test  for 
syphilis  precisely  as  tuberculin  is  rubbed  into  the  skin 
in  diagnosis  of  tuberculosis.  He  claims  good  results 
during  the  later  stages,  but  as  a  diagnostic  test  of 
recent  infection  it  has  not  yet  proven  of  value. 

Chancroid. — There  is  a  venereal  disease  known  as 
chancroid  or  soft  chancre  in  contradistinction  to  the 
primary  hard  chancre  of  syphilis.  This  is  an  acute 
infectious  condition  due  to  the  bacillus  of  Ducrey. 
The  lesion  begins  as  a  pustule,  which  soon  breaks 
down  into  a  spreading  ulcer.  The  disease  is  communi- 
cated by  direct  contact  usually.  The  bacilli  are  in  the 
discharges  and  therefore  can  be  transferred  through 
the  intervention  of  dressings.  The  bacilli  are  extremely 
small,  double  rods,  not  motile,  and  form  no  spores. 
These  grow  on  laboratory  media  containing  blood. 
They  do  not  possess  a  great  viability  under  artificial 
conditions,  and  therefore  are  destroyed  in  discharges 
quite  easily.  Simple  drying  seems  to  kill  them  shortly, 
and  weak  solutions  of  the  ordinary  disinfectants  are 
quickly  efficient.  We  assist  in  the  clinical  diagnosis 
of  chancroid  by  finding  the  diplo-rods,  mostly  within 
leukocytes,  in  scrapings  from  the  depth  of  the 
ulceration. 

BACTERIUM  LEPItffi 

Leprosy  is  a  chronic  endemic  infectious  disease 
characterized  by  the  development,  in  the  skin  chiefly, 
but  also  the  mucous  membranes,  of  firm  nodules  and 


152     THE  MORE  CHRONIC  INFECTIOUS  DISEASES 

diffuse  swellings  due  to  the  growth  and  irritation  of 
the  Bacterium  leprce  or  leprosy  bacillus. 

Forms  of  Leprosy. — There  are  two  forms,  the  nodular 
and  anesthetic.  The  former  is  usually  painless  through- 
out its  course,  merely  giving  rise  to  the  cutaneous 
nodules.  The  anesthetic  form  is  due  to  an  involvement 
of  the  sensory  nerves,  which  are  at  first  irritated  with 
the  production  of  a  painful  early  stage,  followed  by 
destruction  of  sensation  when  the  inflammation  has 
progressed  farther.  The  disease  gives  rise  to  con- 
siderable superficial  destruction  of  tissue,  which  is 
responsible  for  the  horrible  pictures  of  this  disease 
in  the  lay  mind.  Fingers,  toes,  nose,  and  pieces  of 
skin  may  be  removed  by  ulceration.  The  disease  is 
an  old  and  widespread  one  commonest  in  the  tropics, 
but  by  no  means  confined  to  them.  Despite  long 
familiarity  with  leprosy,  there  are  many  points  as  yet 
undecided  about  its  nature. 

Transmission. — The  bacteria  probably  enter  by  the 
nose  and  mouth,  and  it  requires  close  association  with 
a  leper  for  a  long  time  in  order  to  contract  the  disease. 
The  low  contagiousness  of  leprosy  should  be  empha- 
sized. If  one  should  say  in  a  crowd,  "There  is  a 
leper!"  the  people  would  shun  him  as  if  he  were  a 
maniac  with  a  firearm.  If  one  were  to  say  under 
similar  conditions,  "There  is  a  consumptive!"  he 
would  be  pitied  and  perhaps  not  avoided  at  all.  Tuber- 
culosis is  vastly  more  easily  transmitted  than  leprosy. 
The  inhuman  treatment  accorded  to  lepers  is  due  to 
this  misapprehension.  The  disease  is  probably  not 
hereditary. 

When  the  bacteria  enter  the  mucous  surfaces  thev 


BACTERIUM  LEPUM  153 

are  carried  by  the  lymph  or  blood  to  the  exposed  skin 
surfaces,  chiefly  the  face  and  hands.  Here  they  settle 
in  the  subcutaneous  tissues  and  nerves,  producing  a 
chronic  inflammation  in  which  lepra  cells  are  found. 
These  are  large  round  or  oval  cells,  crowded  with 
bacilli,  lying  irregularly  throughout  the  inflammatory 
tissues.  Leprosy  does  not  form  definite  tubercles 

FIG.  43 


Schematic  representation  of  section  through  a  lepra  nodule:  left  side  of 
picture  gives  appearance  under  low  magnifying  power;  right  side,  the  appear- 
ance when  highly  magnified.  In  the  latter  the  large  lepra  cells  are  diagram- 
matically  indicated.  (Abbott.) 


like  tuberculosis,  but  the  process  is  more  diffuse;  nor 
does  caseation  occur.  Giant  cells  are  uncommon. 
The  bacilli  produce  these  changes  largely  by  poison 
in  their  body  and  by  mechanical  irritation.  There  is 
some  reason  to  believe,  by  most  recent  researches, 
that  a  soluble  or  extracellular  poison  is  formed.  The 
bacteria  are  discharged  from  the  patient  by  the 


154     THE  MORE  CHRONIC  INFECTIOUS  DISEASES 

sloughing  of  wounds,  especially  the  ulcers  in  the  nose 
and  throat.  The  dressings  and  cloths  used  to  wipe 
the  nose  should  be  burned.  Intimate  contact,  such  as 
sleeping  with  or  kissing  lepers,  should  be  avoided. 
The  diagnosis  is  made  by  finding  the  rods  in  their 
peculiar  cells,  which  is  best  achieved  by  removing  a 
piece  of  the  skin  growths. 

Morphology  and  General  Character. — The  leprosy 
bacillus,  like  the  tubercle  bacillus,  is  stained  with 
difficulty,  and  belongs  to  what  are  called  the  acid-fast 
bacteria.  Methods  similar  to  that  described  for 
tubercle  bacillus  must  be  used,  but  the  determination 
is  by  no  means  simple  even  to  the  most  experienced 
bacteriologists.  The  similarity  to  the  tubercle  bacillus 
is  further  shown  by  the  fact  that  the  tuberculin  skin 
test  is  positive  in  lepers.  A  poison  similar  to  tuber- 
culin, called  leprin,  has  been  made  by  extracting 
leprous  tissue.  It  is  only  within  the  last  year  that 
the  pure  direct  cultivation  of  Bacterium  leprce  has 
been  successful,  and  then  only  upon  special  media 
with  a  very  delicate  technique.  More  about  the 
poisons  will  probably  be  learned  in  the  near  future. 
The  bacillus  of  leprosy  is  a  straight  rod  with  rounded 
ends,  a  trifle  smaller  than  the  tubercle  bacillus.  Its 
resistance  to  chemicals  and  heat  is  probably  the 
same  as  that  organism.  It  grows  only  at  body  tem- 
perature. Some  attempts  have  been  made  to  use 
devitalized  leprous  tissue  and  the  vaccines  from  the 
tubercle  bacilli  as  a  remedy.  These  have  met  with 
indifferent  success. 

Acid-fast  Bacteria. — The  two  organisms  of  tuber- 
culosis and  leprosy  are  members  of  the  acid-fast  group. 


BACTERIUM  MALLEI  155 

There  are  numerous  other  bacteria  that  stain  and  are 
decolorized  with  difficulty,  but  these  are  the  impor- 
tant disease  producers.  Such  an  organism,  called  the 
Bacterium  smegmatis,  exists  in  the  smegma  about  the 
genitals,  and  is  often  a  source  of  confusion  when 
examining  for  tuberculosis  of  the  urogenital  apparatus. 
It  does  not  produce  disease,  however.  It  is  possible 
also  to  exclude  it  by  a  special  staining  method.  Other 
acid-fast  bacteria  exist  in  manure,  hay,  and  butter. 

BACTERIUM  MALLEI 

Glanders  is  chiefly  a  disease  of  horses,  characterized 
by  nodular  growths  and  ulcers  in  the  upper  air  passages 
or  diffuse  swellings  under  the  skin.  In  the  latter  form 
it  is  called  farcy.  The  causative  organism  is  the 
Bacterium  mallei  or  glanders  bacillus.  Human  beings, 
who  are  associated  with  horses  or  who  work  in  the 
laboratory  with  cultures,  may  contract  the  disease; 
usually,  however,  in  the  acute  form,  whereas  the  lower 
animals  commonly  have  a  protracted  attack.  The 
bacteria  enter  by  small  cracks  or  wounds  in  the  mucous 
membrane  of  the  mouth  or  nose,  and  are  carried  by 
the  lymph  or  blood  to  subcutaneous  tissues.  Whether 
they  produce  glanders  proper  or  farcy,  they  stimulate 
the  tissue  to  produce  nodules  not  unlike  the  tubercle, 
but  of  more  rapid  progression.  Quite  early  they 
break  down  into  abscesses  or  through  the  skin  as  large 
sloughing  ulcers.  The  poisons  are  almost  entirely  endo- 
toxins,  and  may  be  extracted  from  cultures.  A  slight 
amount  of  resistance  is  gained  by  passing  through  an 
attack. 


156      THE  MORE  CHRONIC  INFECTIOUS  DISEASES 

Diagnosis. — Agglutinins  are  formed  in  the  blood  and 
the  clumping  test  is  a  valuable  means  of  diagnosis. 
The  bacteria  may  also  be  found  by  making  smears  and 
cultures  from  open  ulcers  or  by  withdrawing  some  of 
the  pus  from  an  abscess.  This  pus  may  be  injected 
into  the  peritoneal  cavity  of  a  guinea-pig,  obtaining 
as  evidence  of  the  presence  of  the  Bacterium  mallei 
an  inflammation  of  the  testis.  The  most  practical 
method  of  diagnosticating  glanders  is  by  the  use  of 
the  mallein  test.  Mallein  is  the  poison  elaborated 
by  the  Bacterium  mallei  in  laboratory  cultures.  It  is 
comparable  to  tuberculin,  and  may  be  used  like  it,  by 
injecting  it  under  or  by  rubbing  it  upon  the  skin. 
Reactions  of  temperature  or  reddening  of  the  skin  indi- 
cates the  presence  of  glanders.  The  bacilli  may  be 
found  also  in  stained  smears  of  the  pus  lying  in  pairs 
on  end  within  the  large  so-called  epithelioid  cells. 
Blood  cultures  sometimes  give  a  growth.  The  disin- 
fection of  human  material  should  consist  in  burning  all 
dressings  from  ulcers  or  cloths  used  to  wipe  the  nose 
or  mouth.  Bacteria  leave  the  body  only  with  the 
purulent  discharges.  Strong  antiseptics  such  as  1 
per  cent,  carbolic  acid  should  be  used  for  the  hands 
and  objects  possibly  soiled  by  discharges.  Glanders 
is  a  very  infectious  disease,  and  the  bacilli  are  per- 
tinacious. 

Morphology  and  General  Characteristics.  —  The 
glanders  bacilli  are  straight  or  slightly  curved  rods, 
usually  single,  but  also  in  pairs  or  short  filaments,  and 
measure  from  2i)1ro  o~  to  suVo"  mcn  in  length  and  from 
TFoVoT  to  ^o"o-o"o"  mch  m  width.  They  stain  with 
reasonable  ease.  They  grow  at  37°  C.  or  9S°  F.  very 


BACTERIUM  MALLEI  157 

much  better  in  the  presence  of  oxygen  than  in  its 
absence.  They  do  not  form  spores  nor  are  they  motile. 
They  are  killed  at  55°  C.  or  130°  F.  in  ten  minutes;  by 
1  to  1000  bichloride  or  1  to  100  carbolic  acid  in  ten 
minutes.  After  drying  they  may  live  for  ten  days,  but 
do  not  live  long  in  nature  outside  the  animal  body. 
They  are  easily  grown  upon  most  of  the  laboratory  food- 
stuffs. Most  of  the  lower  animals  are  susceptible  to 

FIG.  44 


Glanders  bacilli.    Agar  culture.     X  1100  diameters.     (Park.) 

glanders  and  it  is  of  some  importance  in  menageries. 
The  disease  in  animals  is  like  that  described  for  per- 
sons, and  the  beasts  do  not  develop  anything  in  their 
blood  which  can  be  used  to  treat  human  beings.  Vac- 
cines are  not  successful  probably  because  the  disease 
in  people  is  too  acute  to  be  amenable  to  a  treat- 
ment with  mallein  comparable  to  that  described  for 
tuberculin. 


158     THE  MORE  CHRONIC  INFECTIOUS  DISEASES 

BACTERIUM  ANTHRACIS 

Anthrax  or  woolsorters'  disease  or  splenic  fever  is 
chiefly  an  acute  infectious  disease  of  animals  caused 
by  the  Bacterium  anthracis  or  anthrax  bacillus.  It  is 
contracted  by  human  beings  through  association  with 
infected  animals,  hides,  wool,  rags,  and  the  like.  It 
is  not  uncommonly  fatal  to  persons.  It  is  expressed 
as  superficial  abscesses,  pustules,  or  carbuncles  scat- 
tered over  the  skin,  or  as  softening  of  the  spleen, 
hemorrhages  into  the  intestinal  wall  and  some  other 
of  the  organs,  even  the  brain.  The  woolsorters' 
disease,  or  pulmonary  form,  occurs  from  inhaling 
bacilli  into  the  lungs.  The  bacteria  enter  by  the 
inspired  air,  by  swallowing,  or  by  wounds  and  cracks. 
However  they  enter  they  spread  by  contiguity  or 
by  the  lymph.  Their  chief  action  is  local.  They 
do  not  enter  the  blood  stream  except  near  death. 
They  do  not  settle  in  one  place  and  remain  there, 
but  may  pass  from  one  localization  to  another.  Their 
action  is  due  to  a  soluble  or  extracellular  toxin.  This 
attacks  any  tissue  and  causes  the  accumulation  of 
edema  and  blood.  The  softenings  are  due  to  the 
killing  effect  of  the  bacillus  poisons  upon  the  tissues. 
This  solvent  action  also  attacks  the  walls  of  blood- 
vessels permitting  the  leaking  of  blood  or  a  true 
hemorrhage.  The  poisons  are  further  absorbed  by  the 
circulation  with  a  resulting  fever  and  general  illness. 
The  bacteria  may  leave  the  body  with  pus  or  sloughs, 
by  the  expectoration  in  the  pulmonary  form,  or  by  the 
feces  when  the  infection  is  intestinal  or  has  become 
generalized. 


BACTERIUM  ANTHRACIS  159 

Protection  against  anthrax  is  secured  with  difficulty 
since  its  organisms  produce  resistant  spores.  The 
sputum,  feces,  and  wound  discharges  should  be  so 
received  that  immediate  burning  is  possible.  Chemical 
disinfection  is  much  less  reliable.  Five  per  cent, 
carbolic  acid  should  be  allowed  to  remain  in  contact 
with  infective  material  for  two  days.  Corrosive 
sublimate,  1  to  1000,  for  one  day  is  usually  sufficient. 

Anthrax  is  diagnosticated  by  finding  the  bacteria, 
not  a  very  difficult  matter  since  they  grow  with  com- 
parative luxuriance  on  laboratory  media.  Smears 
also  assist  because  of  the  characteristic  appearance 
of  the  rods.  During  an  attack  a  human  being  or  an 
animal  produces  no  specific  changes  in  the  blood  or 
tissues  having  a  relation  to  immunity. 

Morphology  and  General  Characteristics. — The  anthrax 
bacillus  is  a  large  straight  rod  with  sharply  cut  ends. 
It  measures  -^-^  to  ^Vfr  inch  long  by  YFUTFTF  to 
2"oiro"o  mcn  wide.  It  does  not  possess  motility,  but 
does  form  spores.  These  are  round,  oval,  or  elliptical, 
and  situated  near  the  centre  of  the  rod.  The  bacilli 
may  grow  in  chains  suggesting  bamboo  sticks.  They 
require  oxygen.  The  rods  but  not  the  spores  are  easy  to 
stain.  They  show  a  delicate  capsule  about  the  organ- 
isms when  stained  in  pus.  They  grow  best  at  37°  C. 
or  98°  F.,  but  also  at  lower  temperatures.  The  vegeta- 
tive rods  are  killed  at  54°  C.  or  130°  F.  in  ten  minutes; 
the  spores  are  killed  by  boiling  ten  minutes  or  in  dry 
heat  at  140°  C.  or  285°  F.  for  ten  minutes.  The 
resistance  to  chemical  agents  has  been  considered  on 
page  51.  It  is  best  not  to  rely  on  any  chemical  killing 
of  anthrax  spores,  as  different  cultures  vary  in  resist- 


160      THE  MORE  CHRONIC  INFECTIOUS  DISEASES 

ance  and  the  environment  plays  an  important  part. 
Anthrax  bacilli  grow  well  and  characteristically  on 
laboratory  culture  media.  It  is  not  possible  to  pro- 
duce a  passive  immunity  to  anthrax.  Among  the 
great  achievements  of  Pasteur  was  the  discovery  of  a 
method  of  rendering  sheep  immune  to  anthrax.  He 
discovered  that  by  growing  anthrax  bacilli  at  a  tem- 
perature of  42°  C.  or  106°  F.  instead  of  37°  C.  or  98°  F. 
he  was  able  to  considerably  reduce  their  virulence. 

FIG.  45 


Threads  of  Bacterium  anthracis  containing  spores.     X  about  1200  diameters. 
(Abbott.) 

By  varying  the  length  of  time  of  cultivation  at  this 
temperature,  two  different  strengths  were  obtained. 
He  now  injected  the  weaker,  and  followed  a  few  days 
later  with  the  more  virulent.  The  resistance  of  the 
animal  can  thus  be  raised  to  a  high  level  for  about  a 
year.  The  'method  is  not  practicable  for  human 
beings. 

ACTINOMYCOSIS 

Actinomycosis  or  lumpy  jaw  is  chiefly  a  disease  of 
animals,  but  may  affect  man.  It  is  characterized  by 
the  production  of  large  semisolid  tumefactions  usually 


A  CTINOM  Y  COS  IS  161 

in  the  upper  air  passages  or  their  neighboring  tissues, 
and  in  the  lungs.  It  may  spread  under  the  skin  or 
into  organs.  The  bones  of  the  jaw  are  usually  involved. 
Any  bone  in  the  path  of  progression  of  the  disease 
may  be  infiltrated.  The  organisms  causing  it  belong 
to  the  higher  bacteria,  and  are  called  Streptothrix 
actinomyces  or  ray  fungus,  because  of  their  tendency 
to  spread  out  in  rays.  The  organism  enters  by  way 
of  the  mouth  or  nose  into  cracks  or  wounds.  Asso- 
ciation with  animals  having  the  disease  is  the  method 
of  infection  in  man. 

When  the  germs  enter  they  start  to  proliferate  and 
excite  a  nodule  not  unlike  that  of  tuberculosis.  It 
spreads  by  continuity  outward  and  involves  adjoining 
structures.  The  nodules  soften  in  the  centres  to 
caseous  matter  in  which  small  white  or  gray  masses  of 
the  bacterial  growth  may  be  found.  This  is  the  chief 
source  of  material  by  which  the  diagnosis  is .  made. 
The  large  tumors  ulcerate  through  the  skin  at  times 
and  present  sloughing  areas.  This  is  the  manner  also 
in  which  the  infecting  germ  leaves  the  body.  In 
diagnosticating  the  disease  one  of  the  small  granules  in 
the  pus  is  taken,  crushed  beneath  a  glass,  and  examined 
directly  under  the  microscope  for  the  ray  fungus.  The 
specimen  may  also  be  stained. 

Infective  material  from  abscesses  or  ulcers  or  the 
sputum  should  be  burned.  Chemical  destruction  is 
less  reliable.  Ordinary  care  of  the  hands  will  suffice 
as  a  protection,  but  no  lack  of  care  is  justifiable.  It 
is  not  a  very  infectious  disease,  but  a  serious  one  and 
one  of  long  duration.  The  peculiar  changes  in  this 
disease  are  due  to  the  life  and  growth  of  the  fungus  as  a 
11 


162     THE  MORE  CHRONIC  INFECTIOUS  DISEASES 

foreign  body  and  probably  not  to  any  peculiar  toxin. 
No  immunity  or  peculiar  blood  changes  follow  an 
attack.  The  treatment  is  surgical  and  medical,  the 
latter  being  confined  to  the  use  of  potassium  iodide. 

Morphology  and  General  Characteristics. — The  organ- 
ism of  actinomycosis  is  in  the  form  of  interwoven 
threads,  radiating  from  a  centre,  having  thickened 

FIG.  46 


Actinomyces  fungus  ("ray  fungus"):  left,  as  seen  in  tissues  under  low 
magnifying  power;  right,  a  fungus  mass  examined  fresh  under  higher_ mag- 
nifying power.  (Abbott.) 


or  bulbous  ends.  These  ends  are  important  as  they 
assist  in  species  determination  and  possibly  have  some- 
thing to  do  with  multiplication  of  the  germ.  The 
threads  are  about  75iro  o"  to  ^oiro  G-  mcn  wide,  their 
length  being  very  variable.  The  bulbs  measure  from 
6"o lro"o  to  -g~oVo  mcn  m  width  and  vary  in  length.  They 
grow  with  reasonable  freedom  in  the  laboratory, 


ACTINOMYCOSIS  163 

especially  upon  media  containing  animal  substances  such 
as  blood  serum.  Their  optimum  temperature  is  40°  C. 
or  102°  F.  They  are  killed  at  75°  C.  or  167°  F.  exposed 
ten  minutes.  They  resist  drying  for  a  long  time. 
They  are  extremely  resistant  to  chemical  disinfectants. 
Not  all  animals  are  susceptible  to  actinomycosis, 
but  those  contracting  it  present  about  the  same  type 
of  lesions.  Nothing  in  their  blood  serum  is  of  any 
value  in  treatment  of  human  beings.  Vaccines  are 
not  used. 


CHAPTER    XI 

VARIOUS    PATHOGENIC    BACTERIA    NOT 

ASSOCIATED    WITH    A    SPECIFIC 

CLINICAL    DISEASE 

THERE  is  a  large  class  of  bacteria  capable  of  producing 
various  inflammations  or  infections  that  do  not  follow 
a  constant  or  even  uniform  course.  Surgically  speaking 
they  are  probably  the  most  important  group  aside 
from  the  pus  cocci.  It  is  not  possible  to  make  many 
generalizations  concerning  these  organisms.  The 
results  of  infection  with  them  vary  greatly,  depending 
first  upon  their  own  virulence  and  second  upon  the 
resistance  of  their  host.  Biologically  many  of  these 
non-specific  germs  bear  a  close  relationship  to  species 
giving  a  very  definite  clinical  disease.  In  the  first 
example,  the  colon  bacillus,  this  is  well  illustrated.  A 
certain  group  of  bacteria  is  spoken  of  as  the  typho- 
colon  series.  This  means  that  they  possess  character- 
istics relating  them  to  one  another.  Certain  members 
of  the  series  can  be  separated  only  by  very  careful 
technique,  yet  they  are  capable  of  setting  up  easily 
distinguishable  affections. 

THE  TYPHOCOLON  BACILLI 

The  colon  bacillus  is  the  common  normal  inhabitant 
of  animal  intestines,  particularly  of  the  colon  whence  it 
derives  its  name.  The  group  of  bacteria,  the  typho- 


THE  TYPHOCOLON  BACILLI  165 

colon  series,  to  which  this  organism  belongs  and  of  which 
it  and  the  typhoid  bacillus  are  the  most  conspicuous 
representatives,  embraces  many  species,  subspecies,  and 
varieties.  A  botanical  and  chemical  classification  satis- 
factory to  all  authorities  has  not  yet  been  made.  It  can 
be  said  in  general  that  all  members  of  this  group  find 
the  intestinal  tract  a  suitable  place  for  life,  some  under 
normal,  others  under  pathological  conditions.  Old 
classifications  of  the  typhocolon  group  admitted  only 
organisms  capable  of  motion,  but  some  later  observers 
include  many  non-motile,  and  even  encapsulated  forms. 
Inasmuch  as  a  very  close  separation  on  the  basis  of 
technicalities  is  not  necessary  in  this  work,  it  has 
been  deemed  best  to  choose  the  principal  clearly  defined 
species  for  description.  Such  descriptions  permit  of 
extension  in  a  general  way  to  the  nearest  congeners, 
and  therefore  we  may  say  that  we  are  considering 
types.  The  typhoid  and  paratyphoid  bacilli  have 
been  sufficiently  described  in  Chapter  IX. 

The  Colon  Bacillus. — The  colon  bacillus  proper, 
called  also  the  Bacillus  coli  communis,  is  a  non-spore- 
bearing,  sluggishly  motile,  delicate  rod,  measuring 
from  2Tlroo- to  W<ro  inch  in  length  and 6"oi3~o"o  to  ^-Q-Q 
inch  in  width.  It  appears  when  stained  as  a  single 
rod  usually,  but  occasionally  in  pairs  or  short  chains. 
It  takes  the  laboratory  dyes  with  ease,  usually  more 
deeply  near  its  rounded  ends.  It  moves  by  flagella 
arranged  all  about  the  cell  wall.  It  grows  with  ease 
artificially,  best  in  the  presence  of  oxygen,  but  also 
in  its  absence.  Development  will  occur  at  any  tem- 
perature from  10°  to  43°  C  or  50°  to  108°  F.  It 
produces  no  spores.  No  color  or  pigment  is  developed 


166  PATHOGENIC  BACTERIA 

when  cultivated  in  the  laboratory.  It  possesses  the 
power  of  coagulating  milk  and  of  acid  fermentation, 
with  the  production  of  gas,  in  most  of  the  carbohydrates 
(sugars  and  starches)  used  for  the  differentiation  of 
bacteria.  It  does  not  produce  ferments  capable  of 
liquefying  gelatin  or  the  milk  curd.  It  does,  however, 
break  up  simpler  substances  and  forms  indol,  a  putre- 
factive product. 

FIG.  47 


Colon  bacilli.    Twenty-four-hour  agar  culture.     X  1100  diameters.    (Park.) 

The  colon  bacillus  is  killed  at  60°  C.  or  140°  F.  in 
ten  minutes.  It  resists  freezing  for  a  long  time,  perhaps 
several  months.  Drying  usually  kills  in  one  day,  but 
certain  individuals  may  remain  viable  for  many  days 
or  weeks.  It  is  killed  by  carbolic  acid,  1  to  1000, 
in  twenty  minutes,  or  5  per  cent,  in  two  minutes  in 
watery  suspension.  About  the  same  time  hold  for 
bichloride  of  mercury,  1  to  4000  and  1  to  1000.  To 
weak  acids  it  is  resistant,  as  is  shown  by  its  passage 


THE  TYPHOCOLON  BACILLI  167 

in  food  through  the  hydrochloric  acid  of  the  stomach. 
This  is  also  true  of  the  typhoid  bacillus.  It  will 
multiply  in  feebly  acid  or  alkaline  solutions.  Direct 
sunlight  kills  almost  at  once,  while  diffuse  light  is 
withstood  for  a  long  time. 

The  colon  bacillus  is  found  in  the  intestines  of 
man  and  animals  in  health  or  disease.  It  is  expelled 
with  the  feces  and  therefore  gets  into  water-courses. 
Examination  of  water  for  public  health  purposes 
aims  at  its  discovery  as  an  indication  of  sewage 
pollution.  Its  presence  in  milk  may  be  accounted 
for  by  contamination  of  milk  in  cans  washed  with 
polluted  water.  It  should  not  be  forgotten  that 
despite  the  greatest  personal  care,  colon  bacilli  are 
widely  distributed  on  everything  that  comes  in  contact 
with  man  and  animals.  The  newborn  baby's  intestine 
is  free  of  them,  but  does  not  long  remain  so  as  the 
organisms  find  their  way  in  with  food,  from  the  hands 
of  attendants,  or  possibly  through  the  anus  and  up  the 
rectum.  The  bacilli  may  be  found  in  the  superficial 
layers  of  the  earth.  The  colon  contains  most  of  the 
bacilli  and  the  number  decreases  upward  in  the  small 
intestine  until  in  the  stomach  they  are  rarely  found. 
They  may,  however,  at  times  enter  the  liver  by  means 
of  the  bile  passages  or  portal  vein  system. 

The  constancy  with  which  the  colon  bacilli  are 
present  in  the  intestine  raises  the  question  as  to  their 
function  or  value  there.  This  is  probably  best  answered 
today  by  saying  that  they  assist  in  controlling  the 
growth  of  certain  putrefactive  bacteria,  and  that  they 
may  assist  somewhat  in  breaking  up  simple  substances 
so  that  these  may  be  more  easily  absorbed. 


168  PATHOGENIC  BACTERIA 

The  toxin  of  the  colon  bacillus  is  within  its  body, 
no  extracellular  poison  being  formed.  If  one  inject 
the  dead  organisms  into  an  animal  in  sufficient  number, 
mucous  membrane  irritation,  paralyses,  and  convul- 
sions may  occur.  Living  bacilli  introduced  into  the 
peritoneum  cause  peritonitis  and  septicemia,  the 
organisms  entering  the  blood  stream.  An  abscess  will 
usually  result  if  they  are  brought  under  the  skin.  In 
man  colon  bacilli  seldom  go  beyond  the  mucous 
membrane  of  the  intestine  because  of  the  resistance 
offered  by  that  tissue.  After  death  the  organisms 
rapidly  invade  the  different  organs  of  the  body. 
Whenever  the  resistance  of  the  body  is  reduced  an 
opportunity  is  presented  for  the  spread  of  these 
organisms.  When  sepsis  occurs  there  is  an  inflammation 
of  the  mucous  membrane  of  the  intestine,  a  swelling 
of  Peyer's  plaques  comparable  to  that  seen  in  typhoid 
fever.  There  may  be  inflammation  of  the  gall-bladder, 
the  pelvis  of  the  kidney,  or  abscesses  in  various  parts 
of  the  body.  Cystitis  may  occur  which  may  be  a 
part  of  a  general  infection,  descend  from  the  kidney, 
or  arise  from  introduction  of  the  organisms  through 
the  urethra.  An  ascending  infection  from  the  bladder 
to  the  pelvis  of  the  kidney  and  on  into  the  substance 
of  the  organ  is  not  an  uncommon  disease  process. 
This  frequently  occurs  in  pregnancy  or  after  labor. 

The  inflammations  of  the  gall-bladder  and  its 
passages  and  of  the  liver  may  arise  either  from  intro- 
duction of  bacilli  up  the  common  bile  duct,  or  as  a 
part  of  colon  bacillus  septicemia.  The  peritonitis 
seen  after  perforation  of  the  intestines  is  the  result  of 
manv  kinds  of  bacteria  of  which  the  colon  bacillus 


THE  TYPHOCOLON  BACILLI  169 

may  be  the  most  numerous.  It  is  probable  that  this 
organism  alone  is  able  to  inflame  the  peritoneum,  as 
it  certainly  can  produce  localized  and  diffuse  pus 
collections.  The  colon  bacillus  is  frequently  the  only 
organism  found  in  acute  appendicitis.  It  has  been 
found  as  an  important  factor  if  not  the  sole  cause  in 
pneumonia  and  pleurisy.  It  has  been  found  to  cause 
meningitis  and  endocarditis. 

No  antiserum  of  practical  value  has  been  produced 
by  the  injection  of  these  organisms  into  the  lower 
animals.  On  the  other  hand,  some  success  has  been 
attained  in  establishing  active  immunity  both  as  a 
preventive  and  as  a  remedial  agency  by  injecting 
increasing  quantities  of  dead  bacteria. 

Diagnosis. — Colon  infections  are  diagnosticated  chiefly 
by  finding  the  organism.  They  are  present  in  the 
fibrinous  exudate  or  pus,  and  in  the  blood  in  septi- 
cemia.  We  grow  some  of  this  in  ordinary  nutrient 
broth  or  jelly,  and  isolate  in  pure  culture.  Colon 
bacilli  are,  of  course,  easily  obtained  from  the  stools. 
The  agglutination  or  clumping  test  can  also  be  used 
in  colon  bacillus  infections,  since  agglutinins  are  formed 
during  an  attack.  Pus  or  other  bacteria  containing 
substances  should  be  disinfected  by  mixing  with  5  per 
cent,  carbolic  acid  and  allowing  it  to  act  for  at  least 
one-half  hour. 

Paracolon  Bacilli. — These  organisms  resemble  the 
Bacillus  coli  communis  so  closely  that  only  the  dif- 
ferences need  be  noted.  They  are  more  actively 
motile,  they  do  not  coagulate  milk  but  probably  pro- 
duce alkalinity  in  it;  they  are  capable  of  producing  acid 
and  gas  in  only  three  of  the  sugars.  They  differ  from 


170  PATHOGENIC  BACTERIA 

the  paratyphoid  bacilli  in  their  action  upon  milk' and 
their  greater  ability '  to  ferment  the  carbohydrates. 
These  two  groups,  the  paracolons  and  paratyphoids 
(see  page  118),  are  called  the  intermediates  between 
the  true  typhoids  and  colons.  Their  cultivation  is 
performed  as  outlined  for  the  colon  bacillus.  The 
typical  species  of  this  group  is  the  Bacillus  enteritidis 
of  Gartner  or  the  meat-poisoning  organism. 

The  disease  produced  by  this  bacterium  is  very 
acute,  but  in  some  infections  by  members  of  this 
group  the  disease  may  last  as  long  as  paratyphoid 
fever.  The  bacteria  are  present  in  meat,  probably 
within  the  animal  before  slaughter.  In  Europe  where 
the  refrigerating  systems  are  less  complete  than  in 
this  country,  meat  passes  from  the  butcher  to  the 
consumer  directly,  and  therefore  there  may  be  epi- 
demics when  infected  cattle  are  slaughtered. 

The  bacteria  pass  into  the  intestines,  are  absorbed 
by  their  walls,  and  pass  into  the  blood  stream.  The 
infection  gives  diarrhea  of  the  typhoid  or  cholera 
type,  prostration,  and  sometimes  delirium.  The 
disease  is  usually  transmitted  only  by  meat  in  the 
form  of  cuts  or  as  sausage,  and  these  foods  are  unaltered 
in  color  and  taste  by  the  presence  of  the  bacteria. 

The  toxin  is  peculiar  in  that  it  resists  cooking 
sufficient  to  destroy  the  life  of  the  bacilli  and  drying 
or  smoking  does  not  diminish  its  power.  It  is  an 
endotoxin.  The  bacillus  may  form  pus  and  the  author 
has  seen  it  as  the  cause  of  a  diffuse  pelvic  inflamma- 
tion. When  injected  into  animals  the  paracolon 
bacilli  are  capable  of  giving  rise  to  a  fatal  septicemia 
with  acute  inflammations,  hemorrhages,  and  collapse. 


MUCOSUS  CAPSULATUS  GROUP  171 

The  bacilli  are  found  chiefly  by  examination  of  the 
stools  or  by  cultivation  of  the  circulating  blood  or 
material  from  abscesses.  Infective  material  should 
be  rendered  innocuous  by  the  means  outlined  for  the 
colon  and  typhoid  bacilli  (p.  112). 

A  very  important  means  of  diagnosis  with  all  the 
infections  of  the  typhocolon  group  is  the  agglutination 
test.  These  congeners  produce  agglutinins  having  some 
affinity  for  all  members  of  the  group.  The  method  of 
use  in  this  test  consists  in  finding  that  member  of  the 
group  that  will  be  clumped  by  the  greatest  dilution  of 
the  patient's  serum.  This  organism  is  then  considered 
the  causative  one.  No  practical  remedy  has  been 
found  by  the  use  of  antitoxins  or  vaccines. 

MUCOSUS  CAPSULATUS  GROUP 

This  group  has  been  included  with  the  colons  by 
many  of  the  later  authorities.  Such  a  classification 
is  open  to  some  objection,  but  it  is  quite  proper  to 
discuss  the  organisms  directly  after  the  colon  group, 
since  the  two  types  have  some  things  in  common  and 
both  are  constantly  present  in  the  intestinal  tract. 

The  bacteria  in  question  are  non-motile,  plump, 
straight  rods  without  spores  but  surrounded  by  a 
capsule,  at  least  when  in  the  animal  body.  They 
measure  from  -g-g-J-o-fr  "to  s^Vo"  mcn  m  length,  and  from 
5~o¥TTTr  to  TGTRTO  mcn  m  width.  They  may  be  found 
lying  singly,  but  when  in  the  body  are  commonly 
united  in  pairs  or  short  chains  about  which  one  may 
find  the  capsule.  We  may  find  the  capsule  in  milk  or 
gelatine  cultures.  They  are  easily  stained  by  ordinary 


172  PATHOGENIC  BACTERIA 

dyes.  They  grow  well,  best  at  body  temperature,  but 
also  as  low  as  12°  C.  or  54°  F.,  or  as  high  as  41°  C.  or 
106°  F.  They  are  killed  at  56°  C.  or  133°  F.  in  ten 
minutes.  They  resist  drying  quite  well.  Freezing  is 
rather  rapidly  fatal  to  them.  They  grow  best  in  the 
presence  of  oxygen,  but  may  live  without  it.  All  the 
artificial  cultivations  of  this  group  are  characterized 
by  luxurianqe,  with  a  tendency  to  a  slimy,  smeary,  or 
tenacious  consistency,  hence  the  name  "mucosus." 
None  of  the  group  can  soften  gelatin  or  make  indol. 
They  all  produce  some  degree  of  acidity  in  milk,  but 
not  all  can  curdle  it. 

The  various  members  behave  very  differently  in 
regard  to  sugars  and  upon  these  reactions  they  are 
classified.  The  poison  produced  by  the  bacteria  of 
this  group  is  probably  all  endotoxic.  They  irritate 
the  part  also  mechanically  by  their  presence.  These 
bacilli  are  widely  distributed  in  animal  life,  but  less 
so  otherwise  in  nature.  They  are  transmitted  directly 
from  man  to  man,  by  particles  of  saliva  or  sputum  or 
in  fecal  discharges,  or  in  pus,  which  should  be  disin- 
fected as  given  for  the  colon  bacillus.  Besides  the 
special  conditions  to  be  mentioned  later,  members  of 
this  group  have  been  known  to  cause  pyelitis,  gastro- 
enteritis, peritonitis,  pleuritis,  and  septicemia. 

The  most  important  member  of  the  group  is  the 
Bacterium  pneumonia  of  Friedlander,  a  common  cause 
of  pneumonia,  next  in  importance  for  the  acute  lobar 
pneumonia  to  the  pneumococcus.  The  pneumonia 
is  characterized  by  its  sticky  nature.  It  is  usually 
short  in  duration  and  grave  in  prognosis.  The  bacilli 
may  enter  the  circulation  and  give  rise  to  localized 


MUCOSUS  CAPSULATUS  GROUP  173 

inflammations,  including  abscesses,  elsewhere  in  the 
body.  It  has  been  known  to  cause  nasal  sinus  trouble, 
otitis  media,  endocarditis,  and  meningitis.  The  bac- 
teria are  found  by  blood  or  sputum  culture.  Agglu- 
tination tests  are  not  of  value. 


FIG.  48 


i 

t 


•.:.  '-v.v 

*  •  « 


1   %     * 


'•    <*    *  *  *      ~H 
%  ^ 


Bacillus  mucosus  capsulatus.     (Hiss  and  Zinsser.) 

Two  other  members  of  this  group  associated  with 
disease  in  man  are  Bacterium  rhinoscleromatis  and 
Bacterium  OZCBUOS.  The  former  is  said  to  cause  a  slow 
granulomatous  inflammation  on  the  nose,  mouth,  or 
larynx,  in  which  hard  nodular  swellings  are  formed, 


174  PATHOGENIC  BACTERIA 

containing  large  typical  cells  loaded  with  bacilli. 
Bacterium  ozcence  is  associated  with  fetid  atrophic 
rhinitis  or  nasal  catarrh. 

All  the  mucosus  group  are  moderately  pathogenic 
for  animals,  but  injections  into  these  experimentally 
do  not  call  forth  prototypes  of  the  diseases  in  man. 

FIG.  49 


Bacillus  of  rhinoscleroma.    Section  of  tissue  showing  the  microorganisms 
within  Mikulicz  cells.     (After  Frankel  and  Pfeiffer.) 


Usually  a  septicemia  with  extensive  fibrin  deposit 
on  serous  membranes  results.  The  thick,  stringy,  or 
viscid  character  of  the  exudates  is  peculiar  to  these 
bacteria.  No  antiserum  has  been  produced  to  use  in 
cases  of  disease  caused  by  them,  but  there  have 
been  some  favorable  results  after  injecting  dead 
organisms  during  an  attack. 


MUCOSUS  CAPSULATUS  GROUP 


175 


Bacterium  Bulgaricum. — Another  organism  not  far 
removed  from  the  group  just  described,  of  practical 
if  not  of  pathogenic  importance,  is  the  milk-souring 
bacillus.  There  are  many  varieties,  but  the  one  now 
used  most  is  the  Bacterium  bulgaricum  of  Massol.  It 
has  the  property  of  breaking  up  the  fat  of  milk  and 
producing  lactic  acid.  This  butter  milk  or  sour  milk 

FIG.  50 


Bacterium  bulgaricum.     X  1000  diameters.     (Piffard.) 


is  used  in  intestinal  diseases  (see  p.  35)  at  the  sug- 
gestion of  Metchnikoff.  The  large  quantity  of  lactic 
acid  is  inimical  to  many  disease-producing,  putrefac- 
tive and  fermenting  bacteria  that  elaborate  absorb- 
able  poisons,  giving  rise  to  auto-intoxication.  The 


176  PATHOGENIC  BACTERIA 

organism,  a  large  one,  from  T2~tf  o"o  to  ^.^  inch  in  length  * 
grows  in  chains,  best  at  44°  C.  or  111°  F.,  in  milk,  but 
may  be  cultivated  on  other  media.  The  souring 
of  milk  takes  place  within  twenty-four  hours  if  the 
temperature  be  correct  (see  Chapter  on  Milk). 

Bacillus  Aerogenes  Capsulatus  of  Welch. — A  very 
important  putrefactive  organism  in  the  intestine  is 
the  Bacillus  aerogenes  capsulatus  of  Welch.  This 
organism  grows  only  in  the  absence  of  oxygen.  It  is 
a  large,  straight,  or  slightly  curved  rod,  from  ^3iro"o 
inch  up  to  YIJQ"  inch  long  by  about  ^oirro  mcn  wi^e' 
non-motile,  and  encapsulated.  It  has  the  power  of 
fluidifying  gelatin  and  clotting  milk.  It  is  introduced 
to  the  human  body  by  wounds,  probably,  or  it  may  go 
out  from  the  intestinal  tract  through  a  solution  of  the 
mucous  membrane.  When  lodging  in  the  organs  it 
forms  gases,  giving  an  appearance  to  the  liver  called 
a  foam  or  sponge  liver.  It  has  an  importance  in 
obstetrics  as  gas-infection  sometimes  appears  after 
mechanical  treatment  within  the  uterus.  It  is  prob- 
ably not  pathogenic  to  entirely  healthy  tissue,  but 
when  an  injury  devitalizes  a  part  an  entrance  is 
afforded.  It  is  responsible  for  the  early  bloating  of 
some  cadavers. 

Bacillus  of  Malignant  Edema. — The  bacillus  of 
malignant  edema  is  a  common  inhabitant  of  the  soil 
and  may  be  found  in  dust.  It  grows  only  in  the  absence 
of  free  oxygen,  but  may  be  cultivated  with  ease  in 
the  laboratory  particularly  if  sugar  be  added  to  the 
medium.  It  is  a  long  delicate  rod  measuring  about 
STTTfriF  inch  in  thickness  and  -ginyTF  to  -oVo"  inch  in 
length.  It  moves  by  flagella  arranged  along  the  sides. 


BACILLUS  PYOCYANEUS  177 

Spores  are  formed  about  the  middle  of  the  length. 
These  spores  are  responsible  for  the  great  resistance 
presented  by  the  germ.  The  pathogenic  properties 
are  due  to  a  soluble  separable  toxin.  The  bacteria 
themselves  do  not  enter  the  blood  stream.  At  the 
site  of  inoculation  an  edematous  and  bloody  swelling 
appears  which  in  susceptible  individuals  spreads 
rapidly.  Death  results  from  toxemia.  This  germ  is 
frequently  responsible  for  spontaneous  disease  in  the 
lower  animals,  but  in  man  is  probably  only  introduced 
by  some  mechanical  injury.  It  has  been  known  to  be 
introduced  by  hypodermic  injections  when  a  dirty 
needle  was  used.  Its  most  common  method  of  intro- 
duction is  in  grinding  dirt  into  a  wound  such  as  a 
compound  fracture.  One  attack  confers  immunity 
against  a  second.  All  discharges  or  dressings  should 
be  so  received  that  they  can  be  burned. 

Bacillus  Proteus  Vulgaris. — The  Bacillus  proteus 
vulgaris  is  a  widely  distributed  organism  of  pro- 
nounced putrefactive  powers.  It  is  very  similar  to  the 
colon  bacillus.  It  has  been  encountered  in  abscesses, 
pyelonephritis,  endometritis,  and  peritonitis.  Meat 
poisonings  have  been  traced  to  it.  Its  toxin  is  very 
poisonous.  It  is  frequently  a  harmless  inhabitant  of 
the  intestinal  tract.  It  is  quite  resistant,  and  to  kill 
it  requires  the  most  approved  disinfectants  acting 
over  a  considerable  time. 

Bacillus  Pyocyaneus. — Bacillus  pyocyaneus  is  the 
organism  of  green  pus.  This  bacterium  is  widely  dis- 
tributed on  the  skin  and  mucous  membranes  of  man 
and  animals.  Its  disease-producing  powers  are  low 
and  considerable  reduction  of  resistance  on  the  part  of 
12 


178  PATHOGENIC  BACTERIA 

the  host  may  be  assumed  when  infection  occurs.  It 
may  enter  by  cracks  or  wounds,  and  not  infrequently 
is  associated  with  other  bacteria,  notably  the  pus  cocci. 
The  pyocyaneus  bacillus  is  an  actively  motile  straight 
or  slightly  curved,  non-spore-forming  rod  measuring 
from  2TTOTT  inch  to  -goVo  inch  long  and  y-g-J-g-  Q  inch 
wide.  Its  motility  is  due  to  one  flagellum  placed 
at  one  end. 

FIG.  51 


Bacillus  pyocyaneus.     (From  Kolle  and  Wassermann.) 

It  grows  readily  at  room  or  body  temperature,  best 
in  the  presence  of  oxygen.  On  agar  jelly  it  forms  pig- 
ments which  color  the  growth  itself  and  the  medium 
upon  which  it  is  living.  These  pigments  are  of  two 
kinds,  a  green  one  and  a  fluorescent  one.  They  impart 
a  beautiful  green  fluorescence  to  the  tube  of  culture 
material.  The  bacillus  has  the  power  to  elaborate  a 
gelatine-digesting  and  a  milk-curdling  ferment.  Its 
powers  of  resistance  to  heat  and  chemicals  are  rather 
high.  Materials  to  be  disinfected  should  be  exposed 


BACILLUS  PYOCYANEUS  179 

to  carbolic  acid  or  formaldehyde  solutions  for  half  an 
hour. 

The  poisons  of  the  pyocyaneus  bacillus  are  twofold- 
one  an  endotoxin,  the  other  a  soluble  separable  toxin. 
These  substances,  more  especially  the  latter,  have  the 
power  of  destroying  some  other  bacteria.  The  broth 
culture,  freed  of  bacteria  and  reduced  to  one-tenth 
its  volume,  is  used  sometimes  to  rid  the  throat  of 
persistent  diphtheria  bacilli.  This  is  called  "pyocy- 
anase."  The  toxins  are  more  poisonous  to  animals 
than  are  the  living  cultures.  Most  small  laboratory 
animals  are  susceptible  to  injections  of  the  living 
pyocyaneus  bacillus.  The  bacilli  may  multiply  within 
the  body  and  enter  the  blood  stream.  It  is  maintained 
that  some  part  of  the  toxin  has  the  power  to  destroy 
red  blood  cells. 

The  pyocyaneus  bacillus  may,  by  its  presence  on 
wounds,  delay  their  healing.  It  is  commonest  perhaps 
in  boils  in  the  axilla  and  groin.  It  has  been  found 
in  otitis  media  and  in  gastro-enteritis  of  debilitated 
children.  There  may  be  a  general  sepsis  under  which 
circumstances  pleurisy,  pericarditis,  and  the  like  may 
be  looked  for.  A  diagnosis  is  made  solely  by  finding 
the  pigment-producing  bacillus  in  pus  or  other  exudate, 
or  possibly  by  blood  culture.  Active  immunity  may 
be  produced  in  the  lower  animals  by  exceedingly 
careful  technique,  but  it  has  not  been  found  profitable 
to  use  the  antiserum  upon  human  beings.  We  know 
little  as  yet  of  vaccine  treatment  in  such  infections. 


CHAPTER    XII 
YEASTS  AND  MOULDS 

THIS  chapter  is  devoted  to  a  consideration  of  the 
next  higher  groups  of  the  plant  algae  above  the  bacteria . 
They  are  the  yeasts  or  Blastomycetes  and  the  moulds 
or  Hyphomycetes.  That  there  is  any  sharp  separation 
of  these  forms  from  the  bacteria,  or  even  from  one 
another,  cannot  be  maintained.  There  are  various 
gradations  in  character  from  the  typical  representa- 
tives of  the  groups  toward  the  others,  so  that  there  are 
intermediary  species  incapable  of  classification.  The 
typical  members  of  each  family  have  very  distinct 
criteria  and  about  them  similar  forms  must  be  classified. 

The  yeasts  and  moulds  are  very  widely  distributed 
in  nature,  but  have  but  slight  pathogenic  powers. 
The  former  are  of  importance  in  the  making  of  spiritu- 
ous liquors,  bread,  etc.  The  moulds  have  little  use, 
and  except  for  their  frequent  appearance  as  contami- 
nations, and  in  a  few  diseases,  are  of  little  interest 
to  the  pathologist  or  bacteriologist. 

YEASTS 

Yeasts  are  spherical  or  ovoid  bodies  with  a  doubly 
contoured  wall  and  a  highly  granular  protoplasm  oft- 
times  with  fat  droplets  in  it.  They  measure  from 


YEASTS  181 

TSTT  to  T^TJ  inch  in  length  and  are  about  two-thirds  as 
wide  as  long.  The  characteristic  feature  of  the  yeasts 
is  their  method  of  reproduction,  which  takes  place  by 
a  swelling  out  of  a  part  of  the  cell  wall  like  a  ball,  into 
which  the  protoplasm  flows.  This  is  called  "budding." 
When  the  daughter-cell  arrives  at  the  proper  size, 
the  connection  with  the  parent  dissolves  and  the  new 
cell  is  free.  Spores  have  been  observed  within  the 
yeast  cells,  and  these  develop  into  adult  cells  when  the 
old  cell  ruptures.  Yeasts  grow  upon  nearly  any  organic 
substance  providing  there  is  moisture.  The  best  media 
and  temperatures  vary  with  the  species.  The  kinds 
pathogenic  for  man  grow  best  upon  foodstuffs  con- 
taining simple  sugars,  but  may  thrive  also  on  complex 
substances.  They  are  grown  with  reasonable  ease  in 
the  laboratory,  but  care  must  be  used  to  get  them  in 
pure  cultures  as  their  development  is  slow.  Their 
peculiar  effect  upon  carbohydrate  containing  stuffs  is 
due  to  their  enzyme  which  has  the  power  of  making 
ethyl  alcohol.  How  much  effect  this  has  upon  the 
production  of  disease  in  man  is  not  known. 

Blastomycosis.  The  disease  produced  by  yeasts  in 
man  called  Blastomycosis,  and  the  causative  agent  is 
called  Saccharomyces  Busse,  after  the  man  who  first 
described  it.  By  the  first,  a  genus  name,  it  is  seen  to 
belong  to  the  same  group  as  that  used  for  bread-raising, 
Saccharomyces  cerevisice.  It  is  not  known  just  how 
the  disease  is  contracted,  but  the  yeast  probably 
enters  wounds,  cracks,  or  hair  follicles.  It  penetrates 
into  the  deep  layers  of  the  skin  and  sets  up  abscesses 
of  slow  development  and  spread.  These  may  break 
down  and  leave  a  sluggish  ulcer  which  later  shows  a 


182  YEASTS  AND  MOULDS 

tendency  to  heal.  More  serious  phases  of  this  infection 
are,  however,  met  when  the  lung  is  first  affected.  Then 
a  pneumonia,  ending  in  sepsis  results.  In  these  cases 
the  outlook  is  hopeless.  The  disease  is  probably  due 
wholly  to  the  mechanical  presence  of  the  yeasts.  The 
germs  leave  the  body  in  pus  or  sputum.  They  are 
not  easily  destroyed,  and  all  infective  matter  should 
be  burned.  It  is,  however,  not  a  very  contagious 
disease. 

FIG.  52 


Saccharomyces  Busse.     X  350  diameters.     (From  Kolle  and  Wassermann.) 

There  is  no  antiserum  treatment  and  the  few  cases 
upon  which  vaccines  were  tried  have  not  held  out 
much  promise  in  this  direction.  Yeasts  are  held 
responsible  for  some  diseases  in  lower  animals,  but  the 
question  is  not  yet  settled.  When  injected  into  them 
intentionally  varying  results  are  obtained.  It  can  be 
said  that  they  settle  by  preference  in  the  lungs  and 
spleen. 


MOULDS 


183 


MOULDS 

This  group  is  by  no  means  so  simple  as  the  yeasts. 
The  genuses  vary  in  almost  every  vital  activity.  The 
following  remarks,  therefore,  pertain  to  those  forms 
having  some  importance  in  human  medicine.  The 
moulds  or  branching  fungi  consists  of  long,  interlacing, 
hair-like  threads  called  mycelia  (sing.,  mycelium), 


FIG.  53 


Penicillium  glaucum.     Gelatin  culture.      Spread  stained  with  gentian-violet. 
500  to  1.     (From  Itzerott  and  Niemann.) 

from  which  come  off  end  branches  called  hyphse,  upon 
which  the  reproducing  parts  usually  develop.  These 
mycelia  are  made  up  either  of  one  long  continuous 
cell  with  a  cell  wall,  and  an  easily  distinguishable,  long 
nucleus,  or  they  may  break  up  into  shorter  forms  each 
with  a  separate  nucleus.  Their  length  and  width  are 
so  variable  that  measurements  would  be  misleading. 


184 


YEASTS  AND  MOULDS 


Their  general  naked-eye  appearance  and  size  is  well 
known  to  any  who  have  observed  the  felt-like  or  cottony 
moulds  upon  decaying  organic  matter. 


FIG.  54 


These  two  half-plates  show  three  months'  growth  on  peptone-maltose  agar  of 
t  wo  megalosporon  varieties  of  the  ringworm  fungus .    Natural  size .    (Park . ) 


Multiplication  occurs  in  two  ways.  Upon  the  hyphse 
may  develop  a  reproductive  organ,  the  sporangium, 
containing  spores  that  become  free  upon  its  rupture.  Or 


MOULDS  185 

the  hyphse  may  split  into  segments  giving  off  end  pieces 
as  reproducing  elements,  called  conidia,  the  whole 
giving  the  appearance  of  the  hand  bones,  the  phalanges 
representing  the  conidia  (see  Penicillium  glaucum). 


FIG.  55 


Achorion  Schonleinii.     (Fliigge.) 

These  moulds  enter  by  wounds,  cracks  or  hair  follicles, 
and  develop  in  the  superficial  layers  of  the  skin.  The 
mechanical  irritation  set  up  by  their  presence  is  largely 
responsible  for  the  various  diseases  they  occasion.  To 
be  sure,  they  can  form  enzymes,  but  of  what  impor- 
tance they  are  in  human  lesions  is  not  known.  The 
diseases  are  not  highly  contagious,  but  of  great  ten- 
acity when  once  well  advanced.  Infective  material 


186  YEASTS  AND  MOULDS 

comes  away  in  all  cases  with  discharges,  and  should 
be  burned.  Their  principal  diseases  in  the  human 
being  are  as  follows: 

Ringworm. — Of  this  there  are  two  varieties — ringworm 
of  the  skin,  Tinea  circinata,  and  ringworm  of  the  hairy 
portions,  Tinea  tonsurans  or  Tinea  sycosis.  This  is  due 
to  the  Trichophyton  of  various  species,  depending  upon 
the  size  of  the  spores.  It  is  commonest  in  children 
in  schools,  and  appears  also  where  uncleanliness  pre- 
vails, as  evidenced  by  epidemics  from  a  badly  kept 
barber  shop.  The  fungus  grows  into  the  hair 
sheath  and  inflames  its  base.  The  disease  appears 
characteristically  as  circular,  scaly  patches,  which  are 
rapidly  denuded  of  hair.  This  disease,  as  far  as  known, 
is  only  transmitted  from  man  to  man. 

Favus. — This  disease  is  caused  by  a  mould  called 
Achorion  Schonleinii,  and  affects  chiefly  the  hairy 
portions  of  the  body.  Animals  as  well  as  man  are 
affected,  and  while  it  is  usually  transmitted  from 
person  to  person,  it  is  not  uncommonly  contracted  by 
fondling  affected  cats  and  dogs.  Debilitated  persons 
are  most  susceptible.  The  fungus  penetrates  the  hair 
shaft,  sets  up  a  little  inflammation  which  slowly  spreads, 
and  is  soon  covered  with  a  curious  sulphur-yellow 
concave  crust  called  a  scutulum.  The  place  becomes 
bald  because  the  nutrition  of  the  hair  is  cut  off.  Some 
cases  are  on  record  where  this  fungus  has  spread  to 
all  the  tissues  of  the  body,  doing  damage  by  the  irrita- 
tion of  its  presence. 

Thrush. — Thrush  or  soor  is  a  disease  caused  by  the 
Oidium  albicans,  and  is  characterized  by  the  presence 
of  small  white  patches  on  the  mucous  membrane, 


MOULDS 


187 


usually  of  the  mouth,  in  unclean  or  illy  nourished 
children.  It  may  be  found  in  the  vagina.  It  has  been 
known  to  spread  throughout  the  body. 


FIG.  56 


0 


Oidium  albicans:  g,  conidia;    e,  pus  cells.      (From  Plaut  in  Kolle  and 
Wassermann.) 


Pityriasis  Versicolor. — This  is  a  disease  chiefly  of 
unclean  persons  produced  by  the  development  of 
Microsporon  furfur  in  the  superficial  layers  of  the 
epithelium.  It  may  appear  anywhere  on  the  body, 
but  chiefly  affects  the  short-haired  skin.  It  is  very 
slightly  contagious. 

Diagnosis. — The  diagnosis  of  these  conditions  depends 
upon  finding  the  particular  fungus.  Some  of  the  pus 


188  YEASTS  AND  MOULDS 

from  a  blastomycotic  abscess  or  some  of  the  scales 
from  the  underside  of  the  crusts  of  the  skin  diseases 
produced  by  moulds  is  softened  in  weak  caustic  and 
examined  in  a  moist  condition  under  the  microscope. 
The  single,  or  budding  cells  of  the  yeasts  or  the  branch- 
ing mycelia  of  the  moulds  are  usually  found  with 
ease.  In  case  it  is  desirable  to  cultivate  the  fungi  a 
long  elaborate  technique  is  necessary. 


CHAPTER    XIII 
BACTERIA  IN  AIR,  SOIL,  WATER,  AND  MILK 

BACTEEIA  IN  AIR 

THE  bacteria  naturally  found  in  air  are  not  patho- 
genic, but  consist  usually  of  spore  formers  and  moulds, 
in  other  words,  those  having  some  resistance  to  dryness 
and  sunlight.  There  are  more  in  the  layers  of  the 
atmosphere  near  the  earth,  circulating  in  air  currents 
after  being  raised  in  dust.  When  there  are  no  currents, 
bacteria  tend  to  settle  on  surfaces,  as  they  are  heavier 
than  air.  After  rain  storms  the  atmosphere  may  be 
nearly  free  of  organisms.  More  pathogenic  forms  are 
found  where  people  live  or  congregate,  so  that  air 
currents  produced  by  human  activities  tend  to  increase 
the  bacteria  floating  about.  Colon  bacilli  are  sometimes 
found  in  the  air  above  streets.  Organisms  may  be 
carried  in  currents  set  up  by  coughing  or  blowing. 
This  is  well  shown  by  the  fact  that  tubercle  bacilli 
may  be  found  at  a  distance  of  twenty  feet  in  front  of 
a  coughing  consumptive.  The  practical  application 
of  this  principle  is  the  use  of  moisture  in  dusting  or 
sweeping.  Surfaces  of  a  sick  room  should  be  wiped 
with  a  moist  cloth,  preferably  using  a  disinfectant 
that  will  not  hurt  the  hands.  Bacteria  cannot  leave  a 
moist  surface.  They  may  be  freed  by  the  bursting  of 
bubbles  of  sputum  or  other  infective  fluid.  They  do 


190      BACTERIA  IN  AIR,  SOIL,  WATER,  AND  MILK 

not  travel  far  by  this  means  if  air  currents  be  absent, 
and  there  is  probably  little  danger  from  simple  unpleas- 
ant odors  from  drains  if  protected  from  these  currents. 
Bacteria  are  found  in  air  by  filtering  a  definite  quantity 
of  air  through  cotton  or  sugar.  The  former  is  washed, 
the  latter  dissolved  in  sterile  water,  and  this  is  examined 
as  outlined  under  water. 


BACTERIA  IN  SOIL 

Microorganisms  live  in  the  first  few  feet  of  the  earth 
wherever  moisture  and  a  small  amount  of  nourishment 
are  found.  Pathogenic  forms  are  nearer  the  surface, 
while  deeper  in  pure  saprophytes  are  found.  Bacteria 
are  deposited  from  dust,  water,  and  the  dejecta  of 
animals.  Pathogenic  ones  are  only  to  be  found  where 
animal  life  exists,  while  in  uninhabited  or  untilled 
lands  they  probably  do  not  exist  at  all.  The  denser 
the  population  the  more  disease-producing  kinds  are 
found.  Rain  will  wash  away  soil  and  carry  with  it 
bacteria  into  water-courses.  This  is  of  great  impor- 
tance where  human  dejecta  are  deposited  on  the 
ground. 

Typhoid  fever  epidemics  have  been  known  to  have 
such  an  origin.  Typhoid  germs  can  live  in  soil  for  many 
months.  Vegetables  are  easily  contaminated,  and  if 
eaten  raw  can  transmit  the  disease.  Cholera  vibrios 
have  a  shorter  life  in  this  place.  Anthrax  bacilli  live 
a  long  time  and  cattle  are  sometimes  infected  by 
their  pasture.  Actinomycosis  is  well  known  to  spread 
through  a  herd  because  of  infected  pasture  land. 
The  bacteria  of  soil  are  found  by  planting  some  of  it 


BACTERIA   IN   WATER  191 

in  laboratory  media,  placing  a  part  at  ordinary  tem- 
perature and  another  at  body  temperature.  By  the 
latter  means  the  forms  parasitic  to  animals  are  found. 
Tetanus  bacilli  are,  perhaps,  the  most  widespread 
of  pathogenic  bacteria  in  the  soil.  Their  resistant 
spores  remain  alive  an  unlimited  time.  Persons  going 
barefoot  and  subject  to  wounds  or  bruises,  may  con- 
tract the  disease.  Tubercle  bacilli,  in  dead  persons, 
live  only  a  few  months,  but  when  contained  in  sputum 
spat  upon  the  earth  survive  for  a  long  period. 

BACTERIA  IN  WATER 

In  water  there  are  many  hundreds  of  species,  but 
it  may  be  said  in  general  that  all  the  disease-producing 
kinds  are  in  water  because  discharges  from  human 
disease  have  been  put  into  it.  Of  course  this  may  not 
be  direct,  but  through  the  agency  of  soil  as  mentioned 
above.  Some  bacteria  may  be  carried  into  streams  by 
rain  which  brings  down  the  dust.  Rain  itself  is  nearly 
free  of  germs.  Bacteria  may  be  present  in  water  up 
to  the  billions  without  altering  greatly  its  clearness  or 
giving  it  an  odor.  Of  the  two  water  sources  recognized 
by  hygienists,  ground  water  (deep  wells)  and  surface 
water  (ponds,  lakes,  and  rivers),  the  second  is  by  far 
the  more  important  and  the  more  easily  polluted. 
Large  bodies  of  water,  either  still  or  moving,  tend  to 
rid  themselves  of  bacteria.  In  still  or  slowly  moving 
bodies  such  as  reservoirs,  germs  settle  with  other 
organic  and  inorganic  matters.  For  water-courses  of 
any  character  purification  is  aided  by  changes  in 
temperature  during  the  day  and  night  and  the  very 


192     BACTERIA  IN  AIR,  SOIL,  WATER,  AND  MILK 

efficient  disinfecting  properties  of  direct  sunlight. 
Oxygen  absorbed  from  the  air  also  assists  in  destroy- 
ing bacteria.  There  are  certain  saprophytes  in  water 
and  sewage  capable  of  breaking  up  organic  matter  and 
freeing  oxygen,  which,  either  free  or  in  going  into  com- 
bination with  other  elements  in  chemical  union,  is 
inimical  to  pathogenic  non-spore-forming  bacteria. 

In  this  book  a  word  may  be  useful  as  to  the  means 
of  artificially  purifying  water  for  domestic  purposes. 
For  the  community  water  is  purified  by  settling  in 
reservoirs,  or  by  filtration  through  sand  and  stones, 
sometimes  aided  by  the  addition  of  chemicals.  For 
household  purposes  bacteria  in  water  may  be  removed 
by  house  filters  made  of  porcelain  attached  to  the 
house  supply,  or  what  is  better,  by  boiling.  The  flat 
taste  of  boiled  water  may  be  removed  by  allowing  air 
to  go  through  by  pouring  from  one  container  to  another 
several  times. 

Water  in  a  shallow  vessel,  preferably  of  copper,  will 
be  practically  sterilized  by  an  hour's  exposure  to  direct 
sunlight.  This  is  practicable  for  camping  parties  who 
are  compelled  to  use  water  under  suspicion. 

Principal  Water-borne  Diseases. — The  principal  dis- 
eases transmitted  by  water  are  typhoid,  cholera,  and 
dysentery.  Typhoid  bacilli  may  live  in  water,  espe- 
cially if  surrounded  by  a  bit  of  protective  and  nutrient 
organic  matter,  for  many  weeks.  The  question  is 
often  asked  as  to  how  a  few  germs  in  a  glass  or  two 
of  water  can  cause  typhoid  fever.  As  a  matter  of 
fact,  when  an  epidemic  of  typhoid  is  starting  there  are 
usually  supposed  to  be  many  germs  and  not  a  few 
in  the  water.  What  probably  happens  is  that  a  small 


BACTERIA  IN  WATER  193 

particle  of  organic  matter,  possibly  feces,  is  swallowed. 
This  may  contain  many  thousand  organisms. 

Although  cholera  organisms  live  in  water  a  shorter 
time  than  typhoid  bacilli,  they  are  said  to  be  viable 
for  several  weeks.  Relatively  more  cholera  organisms 
are  discharged  with  a  cholera  stool  than  is  the  case  of 
typhoid  bacilli  in  enteric  fever.  Dysentery  bacilli  live 
only  a  short  time  in  water  probably,  and  the  impor- 
tance of  water  in  the  dissemination  of  dysentery  is  ques- 
tioned by  some  observers.  Certain  it  is  that  some 
epidemics  appear  to  be  water-borne. 

Typhoid  and  colon  bacilli  are  always  present  in 
typhoid  stools.  It  is  hardly  probable  that  the  former 
could  get  into  water  without  the  other.  Moreover, 
the  colon  bacillus  is  present  in  all  alimentary  tracts. 
It  is  more  easily  detected  in  any  mixture  or  solution 
than  any  other  of  the  intestinal  bacteria.  Therefore  it 
is  taken  as  an  indication  of  sewage  pollution  in  water. 
This  may  not  mean  that  typhoid  bacilli  are  present,  but 
merely  that  contamination  of  water  by  sewage  from 
animal  sources  has  occurred.  Whether  from  man  or 
animals,  it  is  obvious  that  dejecta  should  not  come  into 
water  intended  for  human  consumption.  The  methods 
of  water  examination  now  in  use  all  aim  at  the  detec- 
tion of  Bacillus  coll.  Because  of  its  peculiarities  in  the 
fermentation  of  sugars,  certain  media  are  adopted  as 
standards  for  its  isolation.  Water  is  carefully  collected 
and  kept  upon  ice  so  that  no  increase  of  bacteria  will 
occur.  In  the  laboratory  suitable  measures  are  taken 
to  determine  the  whole  number  of  bacteria  and  the 
presence  of  the  colon  bacillus.  The  whole  number  is 
estimated  by  growing  the  water  in  flat  plates  of  agar 
13 


194      BACTERIA  IN  AIR,  SOIL,  WATER,  AND  MILK 

jelly  and  counting  the  number  of  colonies  growing 
in  forty-eight  hours.  It  is  assumed  that  each  colony 
grows  from  a  single  bacterium.  Chemical  examination 
of  water  aims  at  the  determination  of  the  quantity  of 
organic  matter  indicative  of  sewage  pollution.  Stand- 
ards have  been  set  by  sanitarians,  but  they  are  not 
necessary  here. 

BACTERIA  IN  MILK 

Milk  in  the  deeper  parts  of  the  udder  of  the  healthy 
cow  is  probably  wholly  free  from  bacteria.  The  ducts 
of  the  teats,  however,  are  almost  never  free  from  some 
germs,  and  of  course  the  outside  skin  contains  many. 
In  a  diseased  udder  there  may  be  not  only  the  germ 
causing  the  disease,  but  other  intruders  from  the 
outside.  Bacteria  come  into  milk  from  the  cow  her- 
self or  from  the  outside.  The  latter  is  probably  the 
more  important  and  the  factors  which  must  be  con- 
sidered are  the  dirt  on  the  skin,  swishing  of  the  soiled 
tail,  the  soiled  hands  of  the  dairyman,  and  the  cans, 
contaminated  by  manure  or  by  polluted  water. 

Milk  is  a  capital  culture  medium  for  almost  all  bac- 
teria, and  as  it  is  warm  when  drawn,  growth  may  begin 
very  soon.  Unless  the  milk  be  cooled  very  soon,  to  a 
temperature  at  which  bacterial  growth  is  retarded  or 
stopped,  souring  will  occur.  Perfectly  fresh  milk  has  a 
very  slight  restraining  influence  upon  the  development 
of  some  feebler  bacteria,  but  this  power  is  soon  lost 
and  bacterial  growth  may  be  unlimited.  It  is  best  to 
keep  milk  not  above  40°  F.  or  5°  C.,  but  so  low  a 
temperature  is  not  always  possible  to  maintain.  The 


BACTERIA   IN  MILK  195 

consumer  should  strive  to  keep  milk  at  the  lowest 
temperature  practicable.  Cities  are  now  controlling 
their  milk  supply  by  various  regulations  as  to  the 
dairy  management  and  shipping  systems.  The  most 
important  domestic  means  of  having  clean  milk  consists 
in  receiving  it  in  perfectly  clean  bottles  and  keeping 
it  on  ice. 

Pasteurization. — On  account  of  the  lack  of  perfect 
municipal  control  of  the  milk  supply,  it  is  necessary 
to  resort  to  Pasteurization.  This  consists  in  heating 
the  milk  to  60°  or  70°  C.,  140°  to  158°  F.,  for  ten  to 
twenty  minutes,  and  then  cooling  rapidly.  Various 
methods  are  in  use  commercially,  but  this  can  be  done 
very  easily  in  the  home,  using  a  double  boiler  and  a 
thermometer.  Pasteurization  kills  all  but  the  spores 
of  bacteria,  which  are  of  little  danger  if  the  milk  be 
kept  on  the  ice  or  used  shortly.  Some  persons  object 
to  the  use  of  this  heating  because  the  food  value 
of  the  milk  is  reduced  by  making  certain  chemical 
constituents  harder  to  digest.  The  casein  curds  of  milk 
become  tougher  after  boiling.  However,  some  German 
pediatrists  are  now  using  boiled  cows'  milk  for  certain 
intestinal  disorders  of  children.  If  properly  carried 
out,  Pasteurization  does  more  good  than  harm,  and 
has  proven  its  value  by  the  reduction  of  the  death 
rate  from  infantile  diarrhea  in  summer  time.  The 
greatest  objection  anyone  can  raise  to  Pasteuriza- 
tion is  that  it  gives  a  false  sense  of  security.  It 
cannot  be  too  strongly  emphasized  that  any  natural 
antibacterial  power  possessed  by  the  raw  milk  is 
destroyed  by  Pasteurization  and  that  rigid  precautions 
should  be  observed  that  the  heated  milk  is  not  allowed 


196     BACTERIA  IN  AIR,  SOIL,  WATER,  AND  MILK 

to  remain  at  a  temperature  permitting  the  growth  of 
bacteria.  If  kept  below  60°  F.  and  used  within  twenty- 
four  hours  the  consumer  is  probably  safe  at  all  times. 

Spoiling  of  Milk. — In  the  summer  conditions  for  the 
spoiling  of  milk  are  more  favorable  than  in  winter, 
since  the  temperature  is  unfavorable  for  its  preser- 
vation, and  more  dust  and  flies  introduce  bacteria. 
Bottles  in  which  milk  is  served  should  be  washed 
when  empty,  with  cold  water  first,  and  then  boiled  or 
well  scalded.  If  a  small  quantity  of  milk  remain  in 
the  bottom  putrefactive  and  fermentative  bacteria  grow, 
and  dry  on  the  bottle  making  it  harder  to  clean 
subsequently.  Milk  bottles  should  be  considered  as 
possible  carriers  of  disease  and  the  user  should  assume 
his  part  of  the  responsibility  by  cleaning  them  out 
and  not  leave  it  entirely  to  the  milkman.  The  author 
knows  of  one  instance  where  a  milk  bottle  was  used 
as  a  spittoon. 

Souring  of  Milk. — The  souring  of  milk  is  due  to  a 
variety  of  bacteria,  chief  among  which  is  Bacterium 
lactis  aerogenes,  related  to  the  Bacterium  fulgaricum 
described  above.  This  germ  is  ubiquitous.  It  is  not 
pathogenic.  It  produces  a  fermentation  of  the  sugar 
of  milk,  lactose,  into  lactic  acid.  Moulds  may  help  this 
and  oftentimes  lactic  acid  and  ethyl  alcohol  may  be 
formed  side  by  side.  The  latter  predominates  in  the 
carbonated  milks  like  koumys.  Other  bacteria  cause 
clot,  or  precipitation  of  the  casein,  the  forerunner  of 
cheese.  Streptococci  from  the  udder  or  manure  may 
also  help  in  souring. 

To  make  buttermilk  in  the  home  is  a  simple  matter. 
A  quantity  of  whole  or  skim  milk  is  boiled  and  cooled. 


BACTERIA  IN  MILK  197 

A  tablet  containing  the  lactic  acid  bacilli,  a  small 
quantity  of  pure  culture  of  the  organism,  or  a  "starter" 
from  a  previous  making  is  then  added  to  this  cooled 
milk  and  set  aside  in  a  warm  room  (about  75°  F.)  over 
night.  The  result  is  a  rather  agreeable  sour  milk. 
Pharmaceutical  chemists  and  laboratories  are  now 
supplying  tablets  and  cultures  for  this  purpose. 

Diseases  Caused  by  Polluted  Milk. — Many  diseases  are 
believed  to  be  due  to  bad  or  polluted  milk.  If  milk 
merely  carry  the  germs  this  is  easily  understood,  but 
as  is  the  case  in  the  diarrheas  of  infants,  the  trouble 
may  lie  not  with  the  bacteria  introduced  with  the 
milk,  but  with  the  disturbance  of  digestion  caused 
by  the  abnormal  chemical  conditions  brought  about 
by  souring.  These  strange  chemical  substances 
so  pervert  normal  digestion  that  really  pathogenic 
bacteria,  the  dysentery  bacillus  group,  for  example, 
are  able  to  exert  their  noxious  effects.  Streptococci 
commonly  present  in  the  teats,  identical  with  the 
Streptococcus  pyogenes,  are  said  by  some  to  take  advan- 
tage of  this  disturbed  digestion.  The  examination  for 
streptococci  consists  in  simple  staining  and  finding  of 
them  lying  in  or  about  pus  cells.  Health  authorities 
have  rules  covering  this  method  of  examination  and 
the  interpretation  of  results. 

Scarlet  fever,  although  its  cause  is  unknown,  is 
known  to  spread  along  milk  routes  and  has  at  times 
been  traced  to  a  case  on  a  dairy  farm.  Foot  and 
mouth  disease  of  cattle,  another  condition  of  unknown 
etiology,  has  been  found  in  children  drinking  milk 
from  affected  cows.  The  bacillus  of  diphtheria  may 
live  in  milk  a  long  time  and  may  be  carried  along  a 


198      BACTERIA  IN  AIR,  SOIL,  WATER,  AND  MILK 

milk  route.  It  is  said  that  cholera  may  be  transmitted 
by  milk  contaminated  with  polluted  water. 

Typhoid  Fever.  —  Typhoid  fever  may  be  trans- 
mitted by  milk  when  a  case  exists  on  a  dairy  farm  or  a 
dairyman  uses  polluted  water  to  wash  his  cans.  In 
perfectly  fresh  milk  the  germs  do  not  thrive,  but  when 
a  little  older  the  milk  offers  no  resistance  to  their 
multiplication.  If  sour,  the  lactic  acid  and  alcohol  not 
only  inhibit  their  growth,  but  actually  kill  them.  It  is 
frequently  in  the  period  from  cooling  to  distribution  and 
use  that  contamination  occurs.  This  is  done  by  the 
hands  of  dairymen,  shippers,  tasters  (dipping  the  finger 
into  the  milk),  or  by  domestic  servants.  Carriers 
of  typhoid  bacilli  are  a  prolific  source  of  epidemic 
spread  by  milk.  Although  some  sanitarians  discredit 
the  milk  transmission  of  typhoid,  the  following  obser- 
vations are  very  significant  when  taken  together  with 
the  fact  that  the  Bacillus  typhosus  has  been  found  in 
milk.  There  is  a  relatively  greater  number  of  women 
and  children  affected  in  milk-born  epidemics,  while  in 
water  and  general  epidemics  more  men  are  affected. 
Pasteurization  easily  kills  the  typhoid  bacillus. 

Tuberculosis. — The  question  of  the  transmission  of 
tuberculosis  by  milk  is  one  that  has  raised  much  dis- 
cussion, since  Koch  said  that  the  bovine  type  of 
bacilli  does  not  produce  tuberculosis  in  human  beings. 
The  matter  seems  settled  now  that  tuberculosis  in 
the  young  may  be  caused  by  the  bovine  bacillus,  and  is 
most  commonly  located  in  the  cervical  and  abdominal 
glands  and  in  the  meninges.  If  a  cow  have  tuber- 
culosis of  the  udder,  tubercle  bacilli  are  usually  found 
in  great  numbers  in  the  milk.  If  she  have  lesions 


BACTERIA   IN  MILK  199 

elsewhere  she  may  still  excrete  the  bacilli  in  the 
milk,  but  it  is  impossible  to  determine  when  or  in 
what  numbers.  The  natural  corollary  is  not  to  use 
milk  from  a  tuberculous  animal.  Tuberculin  tests 
are  now  being  required  almost  everywhere  when 
permission  to  register  a  milch  cow  is  asked.  No  cow 
giving  a  tuberculin  test  should  be  used  for  a  milk 
supply.  Bacilli  are  also  excreted  in  feces  of  infected 
animals,  and  are  easily  carried  into  the  milkings  by  the 
swishing  tail.  Tubercle  bacilli  of  human  sources  may, 
of  course,  be  in  milk  if  handled  by  a  consumptive. 
Pasteurization  does  not  surely  kill  the  tubercle  bacillus, 
especially  if  surrounded  by  a  bit  of  mucus. 

Examination  of  Milk.- — Milk  is  examined  for  the 
presence  of  colon  bacilli,  and  the  whole  number  of  bac- 
teria just  as  in  the  case  of  water.  For  the  demon- 
stration of  tubercle  bacilli  by  stain  a  special  technique 
is  necessary.  We  usually  inject  some  of  the  milk, 
cream,  or  sediment  into  guinea-pigs,  and  expect 
lesions  in  them.  The  chemical  examination  of  milk 
usually  shows  its  food  value,  which  may  be  affected 
by  bacteria. 


CHAPTER   XIV 

DISEASES    DUE   TO   PROTOZOA 

THERE  are  not  many  recognized  specific  diseases  in 
man  due  to  these  lowest  animal  forms,  but  those  well 
known  are  of  the  greatest  importance,  because  of  their 
prevalence  in  some  parts  of  the  world  and  an  account 
of  the  difficulties  presented  to  medical  treatment.  It 
may  be  said  in  general  that  the  protozoan  diseases  of 
man  represent  a  phase  in  the  life  history  of  the  causative 
microorganism,  and  are  in  fact  stages  through  which 
the  protozoa  pass  in  order  to  fulfil  their  cycle  of  life. 
The  subject  of  protozoology  is  of  enormous  magnitude, 
and  it  is  impossible  to  even  outline  all  the  steps  which 
may  be  passed  through,  in  a  work  like  this.  An  attempt 
will,  therefore,  be  made  to  describe  the  important 
diseases  due  to  protozoa,  with  a  general  statement 
covering  the  morphology  and  life  history  of  the 
organism.  Of  the  many  thousands  of  species  in  nature, 
only  a  handful  are  pathogenic  for  man.  The  disease- 
producing  types  fall  into  the  following  zoological 
families  or  genera:  Sarcodina  (rhizopoda,  amoebae), 
Mastigophora  (Flagellata,  trypanosoma),  Infusoria 
Heterotricha  (balantidium),  Sporozoa  (coccidia,  hemo- 
sporidia,  plasmodium).  The  diseases  we  shall  see  all 
fall  into  these  groups.  They  are  for  the  most  part 
dependent  upon  the  animal  body  for  the  continuance 


AMEBIC  DYSENTERY  201 

of  their  life.  Other  forms  live  in  water,  earth,  decaying 
matter,  or  as  apparently  harmless  commensal  species 
within  the  intestinal  tract  of  animals  from  insects  up. 

SARCODINA 

Amebic  Dysentery. — Amebic  dysentery  is  a  subacute 
or  chronic  inflammatory  disease  of  the  large  intestine, 
caused  by  the  Enlamceba  histolytica  or  dysenteric  ameba. 
It  is  not  definitely  settled  as  to  the  means  by  which 
this  protozoon  is  transmitted,  but  water  is  probably  the 
most  important  method.  The  cells  multiply  in  the  small 

FIG.  57 


Entamceba  histolytica  (Schaudinn)  from  the  stool  of  a  dysentery  patient. 
The  same  individual  showing  two  successive  movements.  The  nucleus 
contains  the  nucleus  and  three  red  blood  cells.  Enlarged  500  to  1.  After 
Jiirgens  (from  Kisskalt  and  Hartmann). 


intestine,  pass  downward,  and  penetrate  the  mucous 
membrane  of  the  colon.  Here  in  the  deeper  layers 
they  set  up  the  inflammation  largely  by  their  presence, 
but  also  by  some  soluble  excretory  substance.  From 
here  they  may  be  carried  throughout  the  body,  and 
give  rise  to  abscesses  notably  in  the  liver.  These  are 


202      DISEASES  DUE  TO  PROTOZOA 

of  long  standing,  and  may  present  work  for  surgical 
interference. 

The  protozoa  leave  the  body  with  the  feces,  which 
to  be  disinfected  must  be  well  treated  with  carbolic 
acid  or  burned.  They  should  never  be  allowed  to 
dry,  because  the  entameba  may  become  more  resistant 
in  a  dry  state,  due  to  a  curious  spore-like  stage.  This 
disease  is  diagnosticated  by  finding  the  parasites  in 
the  feces  or  pus,  which  must  be  kept  at  a  proper  tem- 
perature during  the  examination.  Some  of  the  material 
is  examined  on  a  warmed  plate  and  kept  not  lowerth  an 
77°  F.  all  the  time.  At  this  degree  the  peculiar  move- 
ments of  the  amebse  are  noted  as  a  pushing  out  of  a 
part  of  the  cell  wall  like  a  bud.  This  is  the  pseudopod 
or  false  foot.  This  means  of  progression  enables  the 
organism  to  penetrate  intact  mucous  surfaces  and  pass 
through  sand  filters  impermeable  for  bacteria. 

The  Entamceba  histolytica  is  an  irregularly  shaped 
mass  of  simple  protoplasm  with  a  primitive  structure. 
Its  nucleus  is  usually  single  in  contrast  to  other  amebre. 
It  measures  up  to  -$%-$  inch.  It  moves  and  embraces  its 
food  by  the  pseudopods.  It  reproduces  by  division  or 
by  the  production  of  daughter-cells  within  its  body. 
When  these  are  massed  together  and  held  by  a  cap- 
sule, it  is  said  to  be  encysted.  When  such  cysts  are 
taken  into  the  body  the  intestinal  juices  probably 
dissolve  the  capsule  and  let  the  cells  go  free.  Encyst- 
ment  occurs  when  conditions  for  life  become  unfavor- 
able. Amebse  are  not  killed  by  cold,  but  succumb  to 
60°  C.  or  140°  F.  in  one  hour.  Acids  are  unfavorable 
for  the  growth.  They  are  cultivated  artificially  with 
great  difficulty,  and  are  usually  combined  with  bacteria, 


KALA-AZAR 


203 


in  whose  presence  they  multiply  without  hindrance. 
Only  monkeys  and  dogs  are  susceptible  to  the  amebae 
causing  disease  in  man.  No  therapy  depending  on 
antitoxins  or  vaccines  is  practicable. 

MASTIGOPHORA 

Kala-azar. — In  the  next  group  of  protozoa,  the  flagel- 
lata,  several  are  pathogenic  for  man.     Kala-azar  is  a 


Protozoa  in  a  case  of  tropical  ulcer.      X  1500  approximately.     (Aftei  Wright.) 


peculiar,  slow  disease,  called  by  various  names,  depend- 
ing upon  its  locality — dumdum  fever,  kala-azar,  etc.— 
exhibiting  a  large  spleen,  hemorrhages,  anemia,  and 


204 


DISEASES  DUE  TO  PROTOZOA 


fever.  The  causative  microorganism  may  be  found 
almost  anywhere  in  the  body,  but  chiefly  in  the 
spleen,  whence  it  may  be  obtained  by  puncture  with 
a  needle.  It  is  said  that  bed-bugs  and  mosquitoes 
transmit  the  disease.  The  protozoon  responsible,  Leish- 
mania  Donovani,  is  an  ovoid  or  circular  or  comma- 
like  mass  with  two  nuclei,  and  one  moderately  long 
flagellum  on  the  forward  end.  They  are  from  y^T 


2000 


to 


8000 


inch  long  and  about  two-thirds  as  wide. 


FIG.  59 


Trypanosoma  gambiense.    (From  Calkins.    Preparation  by  F.  W.  Balstack.) 

Trypanosomiasis. — The  next  flagellate  to  cause  dis- 
ease is  the  Trypanosoma,  two  species  of  which  are 
pathogenic  for  man,  causing  a  disease  called  try- 
panosomiasis,  or  sleeping  sickness.  This  affection  is 


TRYPANOSOMIASIS  205 

commonest  in  Africa,  because  of  the  prevalence  of 
the  tsetse  fly  there.  The  protozoa  are  transmitted 
by  the  bite  of  a  fly  within  whose  body  the  blood 
sucked  from  an  infected  person  leaves  the  trypano- 
soma.  The  bite  of  these  flies,  the  tsetse  fly,  becomes 
infective  for  the  well  twenty-four  hours  after  biting 
the  affected,  and  continues  so  for  about  four  or  five 
days.  These  pests  bite  during  the  daytime,  so  that 
protection  and  screening  of  houses  is  insufficient 
usually  to  guard  against  the  disease.  Of  course  the 
infected  persons  as  well  as  the  healthy  must  be  pro- 
tected from  insects.  Inasmuch  as  it  is  thought  that 
some  species  of  trypanosomas  in  the  blood  of  the 
lower  animals  are  infective  for  man,  strict  quarantine 
is  placed  on  animals  within  countries  where  this  disease 
exists,  and  upon  exported  specimens. 

When  the  protozoa  come  into  the  blood  they  are 
carried  throughout  the  body  and  lodge  chiefly  in  the 
lymph  glands,  an  enlargement  of  which  is  an  early 
sign  of  infection.  When  the  disease  is  well  settled 
we  see  progressive  anemia,  weakness,  and  sleepiness, 
whence  comes  the  name  "sleeping  sickness."  The 
end  comes  from  profound  anemia  and  prostration. 
Pains  and  dropsical  collections  are  common.  The 
disease  lasts  a  varying  time.  The  early  stages  are 
slow,  but  when  the  great  depression  begins  it  usually 
progresses  rapidly  to  a  fatal  end.  The  changes  pro- 
duced are  those  of  obstruction  to  the  lymphatic  system 
and  low  grade  chronic  inflammations.  The  micro- 
organisms are  present  in  the  blood,  all  organs,  including 
the  lymph  glands,  and  the  cerebrospinal  fluid.  From 
all  these  places  they  may  be  recovered  in  making  a 
diagnosis. 


206  DISEASES  DUE  TO  PROTOZOA 

Trypanosomas  are  irregular,  elongated,  twisted 
bodies  with  a  large  nucleus  variously  placed,  and  a 
thickened  ribbon-like  edge,  the  undulating  membrane, 
which  starts  as  a  minute  secondary  nucleus  at  the 
hind  end  and  ends  in  a  rather  long  whip-like  flagellum 
at  the  fore  end.  They  range  from  ^oW  mcn 
to  giro  mcn  m  length  and  they  are  about  ysVo  mcn 
wide.  They  move  by  a  sinuous,  jerking,  boring  action. 
Division  takes  place  by  longitudinal  splitting,  probably 
beginning  at  the  hind  end  and  proceeding  along  the 
undulating  membrane.  The  true  nucleus  shows  its 
division  late.  The  human  trypanosoma  has  resisted 
artificial  cultivation  until  very  recently,  and  at  the 
present  time  it  is  very  difficult  to  cause  development  in 
the  laboratory.  Other  forms  of  these  protozoa  have 
been  grown  with  comparative  ease.  Most  animals 
may  be  the  hosts  of  trypanosoma;  in  some  there  will 
be  disease,  in  others  the  organisms  live  as  harmless 
commensals.  The  modern  treatment  consists  in  using 
an  arsenic  preparation  called  atoxyl.  Numerous 
attempts  have  been  made  to  produce  a  serum  by 
injecting  animals  with  trypanosoma.  Sera  thus 
obtained  have  a  slight  beneficial  effect  upon  the  lower 
animals,  but  have  not  proven  of  great  value  with 
human  beings.  The  injection  of  attenuated  culture 
has  raised  the  resistance  of  certain  lowrer  animals. 
The  fact  that  some  resistance  can  be  attained  by 
attempts  toward  the  production  of  active  and  passive 
immunity  indicates  that  trypanosoma  exert  their 
action  by  some  poison.  Whether  it  be  in  their  bodies 
or  elaborated  in  the  juices  about  them  is  not  known. 

Relapsing  Fever. — Relapsing  fever  is  caused  by  the 
Spiroclwta  Obermeieri  transmitted  by  a  mosquito, 


RELAPSING  FEVER  207 

probably  of  the  genus  Culex.  The  spirochseta  circulates 
in  the  blood  during  attacks  and  settles  in  the  spleen 
between  them.  The  disease  is  characterized  by  inter- 
mittent attacks  of  continued  fever  beginning  suddenly, 
lasting  four  to  six  days,  and  ending  by  crisis.  The 
febrile  periods  recur  with  eight  to  ten  day  intervals  of 
freedom  from  symptoms.  Blood  is  examined  during  the 
fever  and  we  find  under  the  microscope  long,  ^QQ~Q 
inch,  delicate,  ^Q^-Q-Q  inch  wide,  wavy  spirals  with 

FIG.  60 


Spirochaeta  Obermeieri  blood  smear.     Fuchsin.      X  1000  diameters.     (From 
Itzerott  and  Niemann.) 

corkscrew  and  undulatory  movements.  They  have 
not  been  successfully  cultivated,  but  it  is  known  that 
they  are  not  very  resistant  to  deleterious  agencies. 
Some  immunity  is  left  after  an  attack,  and  use  has 
been  made  of  the  serum  in  treating  the  sick.  There 
are  several  species  of  this  spirochete,  differing  very 
slightly,  and  to  make  an  antiserum  it  is  necessary  to 
use  many  varieties.  Texas  and  African  tick  fever  are 
due  to  this  genus 


208 


DISEASES  DUE  TO  PROTOZOA 


Trichomonas. — Two  protozoa  of  a  slight  medical 
importance  are  the  Trichomonas  vaginalis,  with  its 
nearly  related  varieties,  T.  intestinalis  and  T.  pulmon- 
alis,  and  the  Lamblia  intestinalis.  These  forms  may 
infest  the  vagina,  intestine,  or  lung,  and  cause  some 
irritation,  probably  not  particularly  inflammatory. 
They  are  held  responsible  oftentimes  for  the  inflamma- 
tion set  up  by  bacteria  gaining  entrance  at  the  site 


FIG.  61 


FIG.  G2 


Trichomonas  vaginalis. 
(Blochmann.) 


Lamblia  intestinalis. 
(Schewiakoff.) 


of  the  irritation  by  the  protozoa.  However,  the 
vaginitis  and  cystitis  caused  by  the  T.  vaginalis  is  a 
serious  matter  in  children.  These  are  usually  pear- 
shaped  bodies,  with  prominent  nucleus  and  well- 
marked  anterior  flagella.  The  trichomonas  has  a 
heavy  undulating  membrane. 


SPOROZOA 

Malaria. — The   most  important  disease   caused   by 
protozoa   is   malaria.     This   is   an   infectious   disease 


MALARIA 


209 


characterized  by  intermittent  chills,  fever,  and  sweats, 
with  prostration  and  progressive  anemia.  It  is  com- 
mon in  lowlands,  where  stagnant  water  collects,  or 
in  the  vicinity  of  slowly  moving  water,  permitting  the 
propagation  of  mosquitoes.  It  is  not  communicable 
by  contact  of  man  to  man.  It  is  the  infestation  of 
the  red  blood  cells  by  a  parasite  having  three  forms, 
belonging  to  the  order  Hemosporidia.  The  parasites 
are  called  the  Plasmodium  malaria,  the  P.  vivax,  and 


Some  of  the  principal  forms  assumed   by  the   plasmodium  of  tertian  fever  in 
the  course  of  its  cycle  of  development.     (After  Thayer  and  Hewetson.) 


the  P.  falciparum.  Three  types  of  attack  corre- 
spond to  the  three  protozoal  species:  (1)  That  which 
gives  chills  and  fever  every  third  day,  the  tertian 
malaria;  (2)  one  where  the  paroxysm  appears  every 
fourth  day,  the  quartan  type;  and  (3)  a  continuous, 
typhoid-like  type,  the  malignant  or  sestivo-autumnal 
fever. 

The  species  vary  in  finer  morphological  details,  but 
they  follow  the    same    course  in  their  transmission 
14 


210  DISEASES  DUE  TO  PROTOZOA 

and  development  in  regard  to  infectivity,  except  that 
they  require  d'ffering  times  for  their  full  development. 
The  female  mosquitoes  of  the  genus  Anopheles  carry 
the  disease  from  one  person  to  another.  They  fly  and 
bite  in  the  early  evening.  These  mosquitoes  may  be 
recognized  by  their  position  on  a  surface.  Their 

FIG.  64 


Egg  of  Culex   (a)  laid   together  in  "small  boat;"  those  of  Anopheles  (6) 
separate  and  rounded.     (From  Kolle  and  Hetsch.) 


FIG.  65 


a  b 

Larva  of  Culex  (a)  hangs    nearly  at  right  angles  to  water    surface;  those  of 
Anopheles  (6)  are  parallel  to  the  surface.       (From  Kolle  and  Hetsch.) 


body  forms  a  large  angle  with  the  surface,  and  the  head 
is  on  a  line  with  the  body.  The  ordinary  mosquito, 
Culex,  stands  parallel  with  the  surface  with  the  head 
bent  down.  Furthermore,  the  wings  of  the  Anopheles 
are  furred  on  the  flat  surface,  while  the  Culex  wings 
are  only  fitted  with  widely  set,  fine  hairs  on  the  edges. 
There  are  many  other  differences,  but  these  will 


MALARIA 


211 


suffice  as  general  guides.  The  female  mosquito  bites 
a  malarial  person  and  receives  the  parasites  into 
her  stomach.  Here  they  undergo  reproduction  by  a 
sexual  process,  and  appear  in  her  venomosalivary 
gland  in  a  condition  ready  for  transmission  to  the 

FIG.  G6 


c  d 

Body  of  Culex  (a)  when  resting  is  held  parallel  to  wall  in  a  curved 
position,  that  of  Anopheles  (6)  stands  at  an  angle  of  about  45  degrees  and  is 
straight ;  wings  of  Culex  (c)  are  generally  not  spotted;  those  of  Anopheles  (d) 
are  spotted.  (From  Kolle  and  Hetsch.) 

next  person  bitten.  This  gland  is  connected  with  the 
biting  apparatus,  and  some  of  its  secretioli  is  left  under 
the  skin  when  the  mosquito  bites  and  sucks  blood.  It 
is  probably  the  secretion  from  this  gland  which  causes 
the  itching  of  the  ordinary  mosquito  bite.  This  repro- 
duction in  the  mosquito  requires  seven  to  ten  days. 
When  a  person  is  bitten  the  parasites,  left  under  the 


212 


DISEASES  DUE  TO  PROTOZOA 


skin,  penetrate  their  cell  of  choice,  the  red  blood  cor- 
puscle. In  the  body  of  this  cell  they  have  the  power 
of  undergoing  an  asexual  division  (see  Fig.  63).  The 
minute  form  swells  into  a  large  body  and  breaks  up 
into  small  spores.  When  this  mass  of  young  forms 
has  reached  a  size  too  great  for  the  red  cell  the  latter 

FIG.  67 


In  Culex  the  palpse  (a)  of  the  female  are  very  short,  of  the  male  are  longer 
than  the  proboscis;  in  Anopheles  the  palpse  (ft)  of  both  sexes  are  about  equal 
in  length  with  the  proboscis.  (From  Kolle  and  Hetsch.) 


bursts,  synchronously  with  which  we  have  the  chill. 
By  this  bursting  young  forms  are  again  set  free  in  the 
blood,  capable  of  entering  other  red  blood  cells.  Of 
course,  not  all  the  cells  are  affected,  but  in  severe  cases 
one  of  every  thirty  red  blood  cells  may  contain  the 
parasites.  As  a  result  of  this,  severe  grades  of  anemia 
result.  The  cycle  of  development  from  the  young  form 


MALARIA  213 

to  the  bursting  requires  forty-eight  hours  for  the  tertian 
malaria  and  seventy-two  hours  for  quartan  malaria, 
while  in  estivo-autumnal  malaria  there  is  a  slowly 
progressive  attack  on  successive  cells  by  a  curious 
extracellular  and  intracellular  crescent-shaped  body. 

The  anatomy  of  these  plasmodia  is  of  great  intricacy, 
and  undergoes  so  many  changes  that  it  is  hardly 
desirable  to  go  into  detail  here.  Suffice  it  to  say 
that  it  is  a  body  when  adult  somewhat  larger  than  a 
red  blood  cell,  full  of  actively  moving  granules.  The 
young  forms  are  homogeneous,  and  are  found  with 
the  greatest  difficulty  except  when  specially  stained. 
They  probably  get  all  their  granules  from  the  destruc- 
tion of  the  red  blood  cells.  Some  adult  forms  have 
flagella  about  their  wall.  The  power  of  producing 
disease  lies  partly  in  their  destruction  of  the  important 
cells  of  the  blood  and  partly  in  a  poison  they  produce. 
The  internal  organs,  especially  the  spleen,  are  injured 
first  by  the  damage  to  the  blood,  and  secondarily  by 
the  extra  work  thrown  on  them  in  trying  to  destroy 
the  parasites.  A  slight  immunity  remains  after  an 
attack.  There  is  a  relative  racial  immunity  among  the 
negroes.  The  cases  that  do  not  wholly  recover  or 
that  have  remote  recurrences  are  said  to  be  harboring 
quiescent  parasites  in  the  spleen.  A  chronic  inflam- 
mation of  this  organ  often  results. 

Diagnosis. — The  disease  is  diagnosticated  by  making 
fresh  or  dried  and  stained  preparations  of  the  blood  and 
examining  them  under  the  microscope.  Should  malaria 
organisms  be  present,  faint,  irregular  shadows  or  larger 
bodies  filled  with  dancing  granules  are  seen  in  the 
unstained  blood,  while  in  stained  smears  fairly  well 


214      DISEASES  DUE  TO  PROTOZOA 

colored  parasites  containing  quiet  granules  will  be 
found.  Animals  are  not  susceptible  to  human  malaria. 
Monkeys  may  be  artificially  infected.  No  antiserum 
or  vaccine  treatment  is  possible  now.  Quinine  is  a 
specific,  and  if  properly  used  will  cure  all  cases.  The 
spread  of  malaria  is  checked  by  preventing  the  propa- 
gation of  mosquitoes.  These  insects  lay  their  eggs  on 
the  surface  of  quiet  water.  The  young  remain  at  the 
surface  of  the  water  when  they  require  air.  Oil  is 
spread  upon  the  surface  of  the  water  and  all  marshes 
are  drained.  No  increase  of  the  insects  can  go  on  if 
these  two  things  are  done. 


CHAPTER    XV 
DISEASES   OF    UNKNOWN    ETIOLOGY 

WHILE  this  book  concerns  itself  with  the  relation 
of  microorganisms  to  disease,  it  is  fitting  that  men- 
tion be  made  of  some  communicable  affections,  in 
which  the  causative  agent  is  not  yet  known.  The 
clinical  observations  upon  these  infections  indicate 
that  they  are  due  to  some  form  of  living  body  which 
present  methods  of  investigation  do  not  permit  us  to 
demonstrate.  It  is  inconceivable  that  so  specific  a 
condition  as  smallpox  should  come  from  anything  but 
a  self  reproducing  agent. 

Smallpox  or  Variola. — This  is  an  acute  infectious  dis- 
ease characterized  by  severe  constitutional  symptoms 
and  a  rash  which  becomes  pustular,  leaving  behind  it 
after  recovery  peculiar  depressed  scars.  It  is  believed 
today  that  the  various  affections  of  man,  cow,  horse, 
and  sheep  are  practically  identical.  Certain  it  is  that 
infection  with  cowpox  will  give  resistance  to  human 
smallpox.  Vaccination  was  formerly  practised  by 
transferring  the  pox  from  person  to  person,  but  now 
fresh  material  is  used  from  a  cow  which  has  been 
artificially  infected  with  cowpox.  Jenner  in  1798  was 
the  one  who  first  developed  the  principle  of  using 
cowpox  in  the  protection  against  human  variola.  The 
exact  cause  of  smallpox  is  not  known.  It  is  supposed 


216         DISEASES  OF  UNKNOWN  ETIOLOGY 

to  spread  by  contact  either  directly  with  the  sick  or 
indirectly  by  objects  having  been  in  contact  with  them. 
Such  objects  are  called  fomites.  Bacteria  are  present 
in  the  pustules  caused  by  vaccination  and  in  the 
eruption  of  smallpox,  but  they  have  been  proven  to 
be  secondary  invaders. 

Rabies  or  Hydrophobia. — This  is  an  acute  infectious 
disease  to  which  nearly  all  animals  are  susceptible, 
characterized  by  slowly  progressive  palsies  and  de- 
lirium. Hydrophobia  means  fear  of  water.  Such 
an  emotion  does  not  exist,  but  animals  merely  avoid 
water  because  they  cannot  swallow  it.  The  cause  of 
rabies  is  excreted  in  the  saliva  and  may  be  transmitted 
by  the  bite  of  a  rabid  animal.  The  virus  is  innocuous 
if  swallowed.  After  having  entered  the  body  the 
virus  travels  to  the  central  nervous  system  and  remains 
there  throughout  the  whole  attack.  The  spinal  cord 
particularly  is  involved.  The  only  evidence  there  is 
of  the  actual  causative  germ  is  the  presence  of  minute 
stainable  granules  in  the  nerve  cells  of  the  brain. 
These  so-called  "Negri  bodies"  are  demonstrated  by 
special  staining  methods.  When  a  dog  is  suspected 
he  is  killed  and  his  brain  removed.  Bits  of  it  are 
stained  for  microscopic  examination  and  other  pieces 
are  made  into  an  emulsion,  which  is  injected  into  the 
brain  of  a  rabbit.  If  rabies  virus  be  present  this 
susceptible  animal  will  die  within  three  weeks  as  a  rule. 

Pasteur  found  a  method  for  protective  inoculation 
treatment  against  rabies.  He  found  that  if  the  spinal 
cord  of  a  rabbit  suffering  from  rabies  were  dried  in  a 
vacuum  it  lost  its  virulence  for  other  rabbits.  If  he 
dried  it  two  weeks  nearly  all  of  the  virulence  was  lost, 


YELLOW  FEVER  217 

but  if  only  two  days  its  strength  was  only  slightly 
impaired.  He  found  that  if  he  inoculated  animals 
with  gradually  increasing  strengths  or  quantities  of 
emulsions  made  from  these  dried  rabbits'  spinal  cords, 
a  certain  degree  of  immunity  was  obtained.  This 
principle  is  now  used  in  treating  persons  bitten  by 
rabid  animals.  The  treatment  is  possible  after  the 
bite  and  the  outlook  is  better  the  sooner  after  infection 
the  treatment  is  begun.  The  spinal  cords  of  rabbits 
are  ground  up  in  glycerine  and  injections  are  made 
under  the  skin.  The  patient  first  receives  a  dose 
from  a  cord  dried  fourteen  days,  then  from  one  dried 
twelve  or  thirteen  days,  then  ten  or  eleven  days,  and 
so  on  until  one  two  days  dried  is  used.  The  mortality 
from  rabies  has  been  greatly  reduced  by  this  method 
of  active  immunization.  At  present  there  is  no  very 
accurate  laboratory  diagnostic  test  in  rabies.  The 
development  of  the  symptoms  must  be  awaited  to 
make  the  diagnosis  in  people  bitten  by  rabid  animals. 
The  ordinary  disinfecting  dressings  of  bichloride  of 
mercury  and  carbolic  acid  solutions  are  worthless  for 
the  bites  of  rabid  animals.  It  is  necessary  to  use 
the  actual  cautery  or  fuming  nitric  acid  in  order  to 
certainly  remove  rabies  virus  from  a  wound. 

Yellow  Fever. — This  is  an  acute  infectious  disease 
chiefly  of  tropical  countries,  characterized  by  great 
prostration,  severe  pains,  hemorrhages,  and  jaundice. 
The  cause  is  not  known.  The  disease  is  transmitted 
by  the  mosquito  called  Stegomyia  calopus,  which  takes 
some  of  the  infective  blood  from  a  patient  and  trans- 
mits it  to  another  person.  Some  cycle  of  development 
of  the  virus  takes  place  in  the  mosquito  because  the 


218         DISEASES  OF   UNKNOWN  ETIOLOGY 

insect  is  only  capable  of  depositing  it  in  a  bite  when 
twelve  days  shall  have  elapsed  since  it  bit  a  yellow  fever 
patient.  More  than  that,  five  days  elapses  between  the 
bite  of  the  mosquito  and  the  appearance  of  the  virus  in 
the  patient's  blood.  Furthermore,  the  patient's  blood 
only  remains  infective  for  three  days.  The  virus  is 
so  small  that  it  will  pass  through  the  unglazed  porce- 
lain filters  used  in  the  laboratory.  Because  of  these 
facts  the  modern  conception  of  yellow  fever  supposes 
a  protozoon  as  the  cause.  There  are  no  laboratory 
diagnostic  measures  nor  as  yet  any  specific  treatment. 
The  spread  of  yellow  fever  is  prevented  by  destroying 
the  breeding  places  of  the  mosquito,  a  difficult  thing, 
since  this  insect  breeds  in  lowlands  and  bushes  and  in 
houses.  It  bites  usually  in  the  late  afternoon. 

Scarlet  Fever  and  Measles. — These  two  easily  com- 
municable diseases  are  transmitted  apparently  by  the 
virus  cast  off  in  scales  from  the  skin.  Nevertheless 
the  specific  causative  agent  is  unknown.  It  has  lately 
been  shown  that  measles  is  transmissible  to  monkeys 
at  some  particular  time  of  the  disease,  which  appears 
from  present  knowledge  to  be  quite  early.  The  most 
recent  researches  fail  to  show  that  measles  scurf  will 
carry  the  disease  to  monkeys.  Streptococci  were  once 
thought  to  be  the  cause  of  scarlet  fever.  It  would 
seem  from  results  obtained  within  the  last  year  that 
these  organisms  may  be  exonerated. 

Typhus  Fever. — Although  this  condition  is  not  under- 
stood clearly,  it  now  seems  that  body  lice,  flies,  and 
ticks  transmit  it. 

Poliomyelitis. — This  is  an  acute  apparently  infectious 
disease  characterized  by  a  mild  constitutional  illness 


ACUTE  ARTICULAR  RHEUMATISM          219 

followed  by  gradually  appearing  and  progressing 
paralyses.  It  may  be  sporadic  or  appear  in  epidemics. 
The  infective  agent  and  its  mode  of  transmission  are 
not  known.  It  probably  enters  by  the  nose  and 
throat.  The  virus  is  present  in  the  blood,  lymph 
glands,  and  especially  in  the  central  nervous  system. 
It  is  so  small  that  it  will  pass  through  porcelain  filters 
such  as  are  used  for  water  purification.  The  disease 
may  be  reproduced  in  monkeys  by  injecting  this  virus 
by  almost  any  route  and  it  is  strictly  comparable  to 
that  seen  in  human  beings.  It  is  not  known  how 
the  virus  leaves  the  body.  There  is  as  yet  no  reliable 
specific  treatment.  The  only  laboratory  test  consists 
in  finding  an  excess  of  clear  cerebrospinal  fluid  in 
which  there  is  a  slight  excess  of  a  certain  organic  sub- 
stance called  globulin  and  a  very  small  number  of  cells. 

Mumps. — This  is  an  acute  inflammatory  infectious 
disease  of  the  salivary  glands,  the  cause  of  which  is 
not  known.  It  is  disseminated  by  direct  contact,  and 
the  virus  is  in  the  saliva. 

Acute  Articular  Rheumatism. — The  modern  concep- 
tion of  this  disease  is  that  it  is  an  acute  infection. 
Many  bacteria  have  been  described  as  its  cause,^  but 
their  defenders  have  not  built  up  unanswerable  argu- 
ments in  their  support.  The  theory  now  holding 
the  stage  is  that  a  streptococcus  called  Streptococcus 
rheumaticus  enters  by  the  tonsils,  penetrates  to  the 
blood  stream,  and  settles  in  the  joints.  Certain  it  is 
that  we  frequently  have  streptococcus  sore  throat 
associated  with  acute  rheumatism,  and  that  the 
inflammations  of  the  heart  lining  after  this  disease 
are  frequently  streptococcal. 


220         DISEASES  OF  UNKNOWN  ETIOLOGY 

Impetigo  Contagiosa. — This  is  an  acute  pustular 
eruption  of  the  skin,  thought,  but  not  proven,  to  be 
due  to  the  pus  cocci.  Some  observers  maintain  that  a 
protozoon  is  the  cause.  At  all  events  pus  cocci,  both 
streptococci  and  staphylococci  are  present.  The  lesions 
are  at  first  pustules,  but  soon  break  down  to  flat  ulcers. 
They  occur  chiefly  upon  the  face.  The  disease  is 
transmitted  by  direct  intimate  contact  such  as  kissing. 
Mild  antiseptics  are  sufficient:  1  to  1000  carbolic  acid 
or  1  to  3000  corrosive  sublimate.  A  salve  of  mercury 
is  usually  prescribed.  Its  importance  is  greatest  in 
surgical  and  children's  wards  and  clinics  and  in  schools. 

Noma  or  Cancrum  Oris. — This  is  a  perforating  ulcer- 
ation,  usually  of  the  cheek,  on  weak  and  debilitated 
children.  It  is  said  to  be  due  to  a  host  of  different 
organisms,  cocci,  pseudodiphtheria  bacilli,  and  many 
others.  The  one  most  frequently  found  is  an  anaerobic 
germ  of  double  appearance,  as  a  rod  and  as  a  spiro- 
cha?ta.  The  treatment  is  of  a  radical  surgical  char- 
acter, as  ordinary  external  applications  are  unavailing. 
It  is  not  very  contagious,  but  discharges  and  sloughs 
are  best  burned. 

Other  Diseases. — Other  diseases  which  human  beings 
may  contract  due  to  invisible  viruses,  are  foot  and 
mouth  disease  of  cattle,  dengue,  trachoma,  beri-beri, 
and  pellagra.  Nearly  all  of  these  viruses  are  small 
enough  to  go  through  a  porcelain  filter.  It  may  be 
said  in  general  that  to  protect  one's  self  from  the  infec- 
tion the  local  lesions  and  skin  eruptions  should  be 
disinfected. 


GLOSSAEY 


THE  meaning  of  many  words  occurring  several 
times  in  the  text  is  given  here  that  the  reader  may  the 
more  intelligently  follow  the  subject  matter.  Certain 
unusual  terms  used  seldom  and  sufficiently  explained 
under  special  headings  are  not  repeated  here.  Nearly 
all  words  in  scientific  language  are  derived  from  Latin 
or  Greek  roots  and  are  to  be  pronounced  precisely 
as  printed. 

Aerobic — Preferring  or  demanding  atmospheric  oxygen 
for  life. 

Agglutinins — Substances  in  the  serum  capable  of  clumping 
bacteria.  Related  words:  to  agglutinate,  agglutination. 

Anaerobic — Preferring  or  demanding  the  absence  of 
atmospheric  oxygen  for  life. 

Anaphylaxis — A  condition  of  high  sensivity  due  to  idio- 
syncrasy to  or  previous  injection  with  certain  organic  sub- 
stances but  otherwise  unexplained  as  yet.  Symptoms: 
shortness  of  breath,  skin  irritations,  and  sometimes  death. 

Antibodies — Substances  developed  in  the  blood  serum 
which  neutralize  all  toxins  of  bacteria,  but  this  word  is 
usually  used  with  reference  to  intracellular  toxins. 

Antitoxins — Antibodies  developed  in  the  blood  serum 
which  neutralize  extracellular  toxins  of  bacteria. 

Asexual — Applied  to  forms  that  can  multiply  without 
being  divided  into  two  separate  and  recognizable  sexual 
elements. 

Attenuate — To  reduce  in  virulence. 


222  GLOSSARY 

Bacillus  (pi.,  Bacilli) — The  genus  of  motile  rods. 

Bacteriaceae — The  family  of  rod-shaped  bacteria. 

Bactericide — A  substance  used  to  kill  bacteria;  also  called 
a  " germicide."  Related  word:  bactericidal. 

Bacterins — The  dead  bodies  of  bacteria  used  to  treat 
disease  by  injection  under  the  skin;  also  called  "vaccines." 

Bacteriolysin — An  antibody  that  will  dissolve  bacteria. 
Related  words:  bacteriolysis,  bacteriolytic. 

Bacteriology — The  study  of  bacteria.  Adj.,  bacterio- 
logical. 

Bacterium  (pi.  Bacteria) — From  Greek  word  meaning  little 
stick;  the  genus  of  non-motile  rods.  The  words  are  also  used 
to  mean  any  of  these  lowest  plants. 

Carrier — A  term  applied  to  a  person  who  carries  germs 
capable  of  being  transmitted  to  and  infecting  others,  but 
himself  not  suffering  at  the  time  from  the  disease  caused  by 
the  germ. 

Cell — The  smallest  recognizable  unit  in  biology.  Cells  are 
single  and  independent  in  bacteria  and  protozoa,  but  are 
combined  and  dependent  upon  one  another  in  the  higher 
plants  and  animals. 

Coccacese — The  family  of  the  spherical  organisms. 

Coccus  (pi.,  Cocci) — A  spherical  organism. 

Colony — The  individual  group  growing  upon  laboratory 
foodstuffs,  and  usually  referring  to  one  small  group.  The 
word  is  used  for  the  growths  upon  flat  dishes  that  are  sup- 
posed to  arise  from  a  single  organism. 

Commensal — Living  in  harmless  union  either  indepen- 
dently or  for  mutual  benefit. 

Complement — A  constituent  of  all  sera  which  helps  in  the 
union  of  antibodies  and  bacteria. 

Cultivation — A  word  used  to  embrace  all  the  procedures 
employed  to  make  germs  grow  under  the  laboratory  con- 
ditions. 

Culture — The  mass  of  bacteria  grown  artificially  upon 
laboratory  foodstuffs.  The  general  term  applied  to  the  way 
bacteria  grow.  See  colony.  Adj.,  cultural. 


GLOSSARY  223 

Cytoplasm — The  soft  part  of  cell  between  the  wall  and 
the  nucleus;  also  called  protoplasm. 

Dejecta — The  feces  and  urine;  also  used  to  mean  sputum, 
sweat,  and  morbid  discharges. 

Disinfection — The  destruction  of  infective  material.  See 
p.  48  for  various  degrees. 

Encystment — The  grouping  together  within  a  resistant 
membrane  of  forms  or  stages  in  the  life  cycle  of  organisms, 
or  a  resting  stage  when  conditions  for  life  are  unfavorable. 

Enzyme — -The  products  of  life  of  organisms  by  which  they 
digest  their  foodstuffs.  A  substance  capable  of  splitting 
others  into  simpler  ones  without  itself  undergoing  any  change 
or  entering  into  the  new  product.  Also  called  ferment. 
Related  words:  enzymic,  enzymatic. 

Etiology — Study  of  the  cause  of  a  disease  and  its  trans- 
mission; also  the  cause  itself. 

Ferment  (pronounced  fer-ment) — See  Enzyme. 

Fermentation — The  breaking  of  sugars  and  starches 
(carbohydrates)  by  bacterial  ferments,  with  the  production 
of  carbon  dioxide,  alcohols,  and  sometimes  acids.  Related 
words:  to  ferment,  fermentative. 

Genus — Next  to  the  lowest  division  of  biological  classi- 
fication, including  members  of  the  lowest  division,  species, 
among  which  there  are  only  slight  differences.  Members 
of  a  genus  must  be  alike  in  all  important  characters.  See 
species. 

Germination — The  progressive  multiplication  of  the  active 
adult  forms. 

Growth— A  word  used  to  cover  the  appearance  of  a  culture 
on,  laboratory  media,  and  sometimes  used  interchangeably 
with  culture. 

Host — The  body  which  carries  a  parasite. 


224  GLOSSARY 

Immunity — The  resistance  of  the  body  to  illness.  See 
p.  64  for  kinds.  Related  words:  to  immunize,  immuni- 
zation, immune. 

Infective — Any  material  carrying  disease  viruses. 

Inhibit — Restrain,  limit. 

Inject — To  put  anything  within  the  body;  in  this  book 
usually  means  to  put  beneath  the  skin. 

Inoculate — To  put  some  infective  material  within  the 
body;  usually  used  in  experimental  work  upon  lower  animals. 

Inorganic — Of  the  mineral  world  and  not  necessarily 
associated  with  living  matter;  example,  salt.  See  organic. 

Isolate — Used  to  indicate  the  procuring  of  germs  from 
morbid  fluids  or  to  the  obtaining  of  a  single  kind,  a  pure 
culture,  usually  by  finding  one  type  of  colony.  Related  word, 
isolation. 

Lesion — Used  to  indicate  any  physical  change  from  normal. 

Leukocytes — The  colorless,  so-called  white  cells  of  the 
blood. 

-logy — A  suffix  meaning  a  " study  of"  the  root,  such  as 
morphology,  which  see. 

Medium  (pi.,  Media) — General  name  given  to  foodstuffs 
upon  which  bacteria  are  grown  artificially. 

Micrococcus — The  genus  of  spherical  organisms  dividing 
in  two  planes. 

Morphology — A  study  of  the  physical  nature,  size,  and 
shape  of  any  object.  Adj.,  morphological. 

Nucleus  (pi.,  Nuclei) — A  mass  within  a  cell  clearly  out- 
lined from  and  denser  than  the  cytoplasm  or  protoplasm, 
and  in  which  the  reproductive  powers  of  the  cell  probably  lie. 

Opsonins — Substances  in  the  blood  serum  which  prepare 
foreign  bodies,  usually  bacteria,  for  consumption  by  the 
white  cells  of  the  blood,  the  phagocytes. 

Optimum — The  best,  most  suitable. 


GLOSSARY  225 

Organic — A  substance  having  the  form,  the  chemistry,  or 
some  characteristics  of  living  matter;  example,  cane-sugar. 
See  Inorganic. 

Parasite — An  organism  living  on  or  in  a  host  to  the  detri- 
ment of  the  latter.  Adj.,  parasitic. 

Pathogenic — Capable  of  producing  disease. 

Pathology — The  study  of  disease — the  broad  subject  of 
the  cause,  production,  and  result  of  disease  and  especially 
the  changes  it  produces  in  the  body.  Related  words:  patho- 
logic, -al. 

Phagocytosis — The  act  of  consuming  foreign  bodies, 
notably  bacteria,  by  the  large  white  cells  of  the  blood,  called 
phagocytes.  Adj.,  phagocytic. 

Plane — The  geometrical  dimension.  There  is  one  plane 
in  a  line,  two  planes  in  a  surface,  and  three  planes  in  a 
body,  such  as  a  cube. 

Plasma — The  fluid  part  of  the  blood  including  the  con- 
stituents capable  of  clotting.  See  Serum. 

Poisons — Used  generally  to  indicate  any  substance  danger- 
ous to  body.  Has  no  particular  significance  for  bacterial 
products  when  used  alone. 

Proliferate — To  multiply,  increase. 

Prophylaxis — Guarding  against  beforehand.  Measures 
toward  preventing  disease.  Adj.,  prophylactic. 

Protoplasm — See  Cytoplasm. 

Protozoa  (sing.,  Protozoon) — The  lowest  order  of  animals, 
independent  single-celled  organisms. 

Pseudo False,  resembling. 

Pseudopods — The  foot-like  projections  of  the  cell  wall 
and  cytoplasm  shown  by  ameba?,  a  method  of  progression 
for  these  protozoa. 

Putrefaction — The  decaying  of  proteid  (the  large  part 
of  meat  and  fish)  with  the  production  of  foul  odors  and 
poisonous  substances.  (This  is  to  be  contrasted  with  fer- 
mentation, which  see.) 

Pyogenes. — Pus-producing.   Adj.,  pyogenic. 

15 


226  GLOSSARY 

Saprophyte — An  organism  capable  of  living  on  dead  or 
decaying  matter.  Adj.,  saprophytic. 

Serum  (pi.,  Sera) — The  clear  light  yellow  fluid  part  of  the 
blood  which  exudes  after  clotting  has  occurred,  and  in  which 
antibodies  reside. 

Sexual — Requiring  two  different  forms  for  reproduction. 

Species — The  lowest  biological  division  of  living  forms, 
varying  only  in  unimportant  characters,  but  possessing  all 
the  characters  of  the  genus  to  which  they  belong.  Lions 
and  tigers  belong  to  the  genus  Felis  (or  cat  family),  but  the 
former  belongs  to  the  species  "leo,"  and  the  latter  to  the 
species  "  tigris. ' '  See  Genus. 

Spirochseta  (pi.,  Spirochaetae) — The  spiral  or  corkscrew-like 
organisms;  name  given  both  to  family  and  genus. 

Staphylococcus — The  spherical  coccus  which  grows  in 
grape-like  masses. 

Sterile — Bacteriologically  speaking,  entirely  free  of  living 
organisms.  A  surgically  sterile  thing  may  contain  organisms 
from  the  air  which  do  not  hurt  the  patient.  Related  words: 
sterility,  sterilization,  to  sterilize. 

Strain — An  individual  culture  of  a  species  isolated  from  a 
case. 

Streptococcus — The  spherical  coccus  which  grows  in  chains. 

Toxins — The  poisonous  products  of  bacterial  life. 
Tumefaction — Any  tumor-like  swelling. 

Vaccine — Originally  used  for  the  inoculation  of  cowpox 
as  a  protective  against  smallpox;  now  used  for  that  and 
for  the  injection  of  dead  or  attenuated  bacteria  for  active 
immunization  or  treatment  during  disease.  See  Bacterins. 
Related  words:  to  vaccinate,  vaccination. 

Viable — Capable  of  living  and  reproducing. 

Virulence — The  power  possessed  by  organisms  to  develop 
.poisons  and  produce  disease.  It  varies  in  different  strains, 
but  depends  also  upon  the  resistance  of  the  host. 

Virus — Any  factor  which  produces  disease,  either  individ- 
ually recognized  or  obscure;  usually  applied  to  poisons  not 
specifically  isolated,  like  rabies  virus. 


INDEX 


A 


ABSCESS,  79 

Achorion  Schoenleinii,  186.  See 

Favus. 

Acid-fast  bacilli,  143,  154 
Acids,  50 
Actinomyces,  161.     See  Strep- 

tothrix  actinomyces. 
Actinomycosis,  160,  163 

bacteriological  diagnosis  of, 

161 
disinfection  during  attack 

of,  161 
in  soil,  190 
transmission  of,  161 
"Active  immunization,"  66 
Aerobe,  221 
Aerobic  bacteria,  34 
Agglutinins,  69,  221 
Air,  bacteria  in,  142,  189 
currents,  189,  190 
examination    of,   for    bac- 
teria, 190 
transmission  of  disease  by, 

142,  190 

Alcohol,  153,  196 
Alga?,  21 

AmebaB,  30,  200,  201 
Amebic  dysentery,  129,  201 
diagnosis  of,  202 
disinfection  during  at- 
tack, 202 
Anaerobe,  221 
Anaerobic  bacteria,  34 
Anaphylaxis,  104,  221 
Anirnalculse,  18 
Animal  inoculation,  41 
Anthrax,  67,  158 
antibodies,  159 


Anthrax,  bacillus,  66,  158 

general  description  of, 

159 
pathogenic  powers  of, 

158,  160 
poisons  of,  158 
relation     of,     to     an- 
thrax, 158 
resistance  to  heat  and 

chemicals,  51,  159 
in  soil,  190 
vaccines,  160 
bacteriological  diagnosis  of, 

159 
disinfection  during  attack 

of,  159 

transmission  of,  158,  159 
vaccines,  160 
Antibody,  67  to  69,  221 
Anti-endptoxins,  67 
Antimeningitis  serum,  94 
Antiseptics,  48 
Antitoxin  unit,  103,  108 
Antitoxins,  65,  67,  103,  108,  221 
Asexual,  221 
Attenuation,  48,  221 
Autoclave,  44 
Auto-intoxication,  35,  175 


B 


BACILLI,  21,  24,  222 

Bacillus    coli     communis,    165. 

See  Colon  Bacillus, 
of  Ducrey,  151.  See  Chanc- 
roid, 
dysenteric,        129.         See 

Dysentery  bacillus, 
enteritidis,  170 


228 


INDEX 


Bacillus  of  Koch-Weeks,  135 
melitensis,  137.    See  Malta 

Fever, 
of    Morax   and    Axenfeld, 

135 

paratyphosus,  118 
pestis,    122.       See  Plague 

bacillus. 

proteus  vulgaris,  177 
pyocyaneus,  177 

diagnosis  of  infections 

with,  179 
general  description  of, 

178 
pathogenic  powers  of, 

177,  179 
poisons,  179 
resistance  to  heat  and 

chemicals,  178 

where  found,  177 

tetani,  105.      See   Tetanus 

bacillus. 

typhosus,    109.     See    Ty- 
phoid bacillus. 
Bacteria,  17,  21,  222 

activities  and  nature  of,  33 
aerobic,  34 
anaerobic,  34 
biological  classification  of, 

21 

capsule  of,  26 
chemistry  of,  31 
colonies  of,  38 
cultivation  of,  38 
cytoplasm  of,  24 
endotoxins  of,  61 
entrance  of,  to  body,  58 
enzymes  of,  34 
extracellular  toxins  of,   61 
in  fermentations,  34 
ferments  of,  34 
flagella  of,  27 
in  hair,  99 

in  intestinal  tract,  33  to  36 
intracellular  toxins  of,  61 
lactic  acid,  36 
motility  of,  26 
nucleus  of,  24 
nutrition  of,  31,  34 
pathogenic,  20 
poisons  of,  60,  61,  68 
in  putrefaction,  34 


Bacteria,  relation  of,  to  disease, 

58 

reproduction  of,  26 
resistance  of  body  to,  59, 

63  to  70,  78 
size  of,  25 
specificity  of,  60 
spores  of,  29 
staining  of,  38 
toxins  of,  61,  67,  68 
transmission  of,  62 
vegetating,  46 
wall  of,  23 
Bacteriacese,  21,  222 
Bactericide,  222 
Bacteriemia,  60 
Bacterin  treatment,  66,  82 
Bacterins,  83,  222 
Bacteriology,  17,  222 
Bacteriolysin,  69,  222 
Bacterium     aerogenes     capsu- 

latus,  176 
anthracis,  158.  See  Anthrax 

bacillus, 
bulgaricum,       175,       176, 

196 

diphtherise,  98.     See  Diph- 
theria bacillus, 
influenza,     118.      See    In- 
fluenza bacillus, 
lactis  aerogenes,  196 
lepra),    151.     See    Leprosy 

bacillus, 
of        malignant       edema, 

176 
mallei,  155.     See  Glanders 

bacillus, 
ozsense,  173 
pneumonias,       172.        See 

Friedlander's  bacillus, 
tuberculosis,       138.       See 

Tubercle  bacillus. 
Balantidium  coli,  200 
Beri-beri,  220 

Bichloride  of  mercury,  49,  53 
Blastomycetes,  21,  180 
diagnosis  of,  187 
disinfection  during  attack, 

182 

transmission  of,  181 
Blood  culture  technique,  74 
Boiling  for  sterilization,  46 


INDEX 


229 


Bordet-Gengou  bacillus,  136. 

See  Whooping  cough 
Boric  acid,  50 
Buttermilk,  196 


CALCIUM,  hydroxide,  50 
Cancrum  oris,  220 
Capsules,  26 
Carbolic  acid,  52,  53 
Carriers,  99,  112,  127,  222 
Caustic  soda,  50 
Cell,  24,  222 
Cellulitis,  79 
Centrosome,  30 
Centigrade  scale,  47 
Cerebrospinal  meningitis,  91 

puncture,    74 
Chancroid,  151 

Chemical  disinfectants,  49  to  53 
practical  uses  of,  53  to 

57 
Chemistry  of  bacteria,  31 

of  protozoa,  32 
Chloride  of  lime,  50 
Chlorinated  lime,  50 
Chloroform,  53 
Cholera,  67,  125 

agglutination  in,  127 
bacteriological  diagnosis  of, 

127 

bacteriolytic  test  for,    127 
disinfection  during  attack, 

127 

spirillum,  61,  127,  193 
agglutinins  of,  127 
carriers  of,  127 
general  description  of, 

128 

in  milk,  198 
pathogenic  powers  of, 

126,  129 
poisons  of,  127 
relation  of,  to  Asiatic 

cholera,  126 
resistance  of,  to  heat 
and  chemicals,    128 
in  soil,  190 
vaccines,  129 
in  water,  61,  193 


Cholera,  transmission  of,  126 
vaccination  against,  129 
Cilia,  30 
Coccacese,  222 
Cocci,  21,  24,  222 
Coccidia,  200 
Colon  bacillus,  80,  165,  189 

diagnosis  of,  infections 

with,  169 
general  description  of, 

165 
pathogenic  powers  of, 

168 

poisons  of,  168 
resistance   of,  to  heat 
and   chemicals,    166 
vaccines,  169 
use  in  intestines,   167 
in  water,  193 
where  found,  167 
Colonies,  38,  222 
Commensal,  222 
Complement,  69,  222 
Conjunctivitis,  gonorrheal,  87 
Koch-Weeks,    135     (pink- 
eye) 

Morax-Axenfeld,  135 
Copper  sulphate,  50 
Corrosive  sublimate,  49 
Cowpox,  215 
Creolin,  52 
Cresols,  52 
Cultivation,  38,  222 
Culture,  222 
Cytoplasm,  24,  30,  223 


DEJECTA,  223 

Dengue,  220 

Diarrhea,  infantile,  from  milk, 

197 
Diphtheria,  98 

administration   of   anti- 
toxin in,  103 
antitoxins,  103, 
bacillus,  61,  65,  98 
antitoxins,  103 
discovery  of,  100 
general  description  of, 
100 


230 


INDEX 


Diphtheria   bacillus    in    milk, 

197 
pathogenic  powers  of, 

99,  102 
poisons,  103 
relation   of,    to    diph- 
theria, 98,  99 
resistance  of,  to  heat 
and   chemicals,    101 
bacteriological  diagnosis  of, 

99,  100 
disinfection  during  attack, 

99 
serum    sickness    following, 

104 

transmission  of,  99,  197 
Diplococci,  26 
Diplococcus     pneumonise,     94. 

See  Pneumococcus. 
Disease,  58 

transmission  of,  62 
water-borne,  192 
Disinfectants,  48 

uses  of,  53  to  57 
Disinfection,  48,  223 
of  dejecta,  54 
of  room  and  houses,  55 
of  sputum,  54 
of  water-closets  and  sinks, 

55 

Dumdum  fever,  203 
Dysentery,  amebic,  129,  201 
bacillary,  129 

antibodies,  131 
antiserum,   133 
bacteriological      diag- 
nosis of,  132 
disinfection         during 

attack,  131 
transmission    of,    130, 

131 
bacillus,  129 

agglutinins,  131 
antisera,  133 
bacteriolysins,   131 
general  description  of, 

132 
pathogenic  powers  of, 

130,  132 
poisons,  130 
relation  of,   to  dysen- 
tery, 130 


Dysentery  bacillus,  resistance 
of,  to  heat  and  chemicals, 
132 


ENCYSTMENT,  223 
Endotoxins,  61,  67 
Entamoeba  histolytica,  201,  See 

Amebic  dysentery, 
general  description  of, 

202 
pathogenic  powers  of, 

201,  203 

Enteric    fever,    109.     See   Ty- 
phoid fever. 
Enzymes,  4 1,223 

in  industries,  36 
Etiology,  223 
Exudate,  80 


FAHRENHEIT  scale,  47 

Favus,  186 

Feces,  collection  of,  73 

sterilization  of,  54 
Fermentation,  19,  34,  41,  196, 

223 
Ferments,  34,  41,223 

in  industries,  36 
Fever,  60 
Flagella,  27,  30 
Flagellata,  200 

Flies,  in  transmission  of  disease, 
63,  110 

tsetse,  205 

Formaldehyde,  50,  51,  54 
Formalin,  50,  51,  54 
Friedlander's  bacillus,  172 

pathogenic  powers  of, 

173 

Fungi,  21 
Furunrulosis,  83 


G 


GENERATION,  spontaneous,  19 
Genus,  223 


INDEX 


231 


Germination,  223 
Glanders,  155  to  157 
bacillus,  155 

general  description  of, 

156 
pathogenic  powers  of, 

155,  157 
poisons,  155 
relation  of,  to  glanders 

155 
resistance  of,  to  heat 

and  chemicals,  157 
vaccines,  157 
bacteriological  diagnosis  of, 

156 
disinfection  during  attack, 

156 

mallein  in,  156,  157 
transmission  of,  155 
vaccines  in,  157 
Glassware,  42 
Glossary,  221 
Gonococcus,  62,  86 

in  conjunctivitis,  87 
general  description  of,  88 
relation  of,   to  gonorrhea, 

86 
resistance  of,  to  heat  and 

chemicals,  88 
Gonorrhea,  86 

bacteriological  diagnosis  of, 

90 
disinfection     during     and 

after  attack,  90 
Gonorrheal  conjunctivitis,   87 

ophthalmia,  87 
Growth,  223 


H 


HAIR,  bacteria  in,  99 

Hanging  drop,  41 

Heat  sterilization,  42  to  47 

Hemosporidia,  200,  209 

Heterotricha,  200 

Host,  21,  223 

Hot  air  sterilization,  47 

Hydrogen  peroxide,  50,   51 

Hydrophobia,  216 

disinfection  against,  217 
Pasteur  tretament  for,  216  | 


Hydrophobia,  transmission  of, 

216 

virus  of,  216,  217 
Hyphse,  183 
Hyphomycetes,  21,   180 


ICE   and   typhoid   fever   trans- 
mission, 111 

Immunity,  63  to  70,  224 
acquired,  64 
active,  64 

acquired,  65 
artificial,  65 
natural,  64 
passive,  64,  65 

acquired,  65 
racial,  64 

Impetigo  contagiosa,  220 
Incubation  period,  62 
Incubator,  40 
Infection,  60 

predisposing  causes  to,  59 
Infective,  224 
Inflammation,  77  to  80 
Influenza,  118 

agglutinins,  120 
bacillus,  62,  91,  118 

general  description  of, 

121 
pathogenic  powers  of, 

119,  121 
poisons,  119 
relation     of,     to     in- 
fluenza, 118 
to  other  diseases, 

119 
resistance  to  heat  and 

chemicals,  121 
vaccines,  121 
bacteriological  diagnosis  of, 

120 
disinfection  during  attack, 

120 

immunity  after  attack,  120 
transmission  of,  119 
Infusoria,  200 
Inhibit,  224 
Inject,  224 
Inoculate,  224 


232 


INDEX 


Inorganic,  224 
Intoxication,  60 
Iodine,  53 

alcohol,  53,  54 
Isolate,  224 


KALA-Azar,  203 
Klebs-Lreffler  bacillus,  98 
Koch- Weeks  bacillus,  135 


LACTIC  acid  bacteria,  35,  175, 

196 

Lamblia  intestinalis,  208 
Leishmania  Donovani,  204 
Leprin,  154 
Leprosy,  151  to  154 
bacillus,  151 

general  description  of, 

154 
pathogenic  powers  of, 

152 

poisons  of,  153 
relation  of,  to  leprosy, 

152 
bacteriological  diagnosis  of, 

154 
disinfection  during  attack, 

154 

forms  of,  152 
transmission  of,  152 
Lesion,  224 
Leukocytes,  69,  224 
Lichens,  21 
Lime,  milk  of,  53 
Lysol,  52 


M 

MALARIA,  208 

diagnosis  of,  213 
estivo-autumnal,  209,   212 
malignant,  209,  213 
prevention  of,  214 
quartan,  209,  211 
tertian,  209,  211 


Mallein,  156 
Malta  fever,  137 

bacilli  in,  137 
general  description  of, 

137 

transmission  of,  137 
Mastigophora,  21,  200,  203 
Measles,  218 

Meat  poisoning  bacteria,  170 
Media,  37,  39,  41,  224 
Meningitis,  90,  91 
antiserum  to,  94 
bacteriological      diagnosis 

of,  93 
coccus,  65,  91 

antiserum,  94 
general  description  of, 

93 

relation  of,  to  menin- 
gitis, 91 

disinfection  during,  92 
Methods  of  examination,  37 
Microbiology,  17 
Micrococcus,  80,  224 

gonorrhoea,  86.    See  Gono- 

coccus. 
intracellularis  meningitidis. 

See  Meningitis  coccus. 
Microscope,  22 

technique  of,  22,  41 
Microsporon  furfur,  187 
Milk,  bacteria  in,  194 

cholera  spirilla  in,  198 
diphtheria  bacilli,  197 
diseases  transmitted  by,  62, 

99,  116,  197 

examination  of,  197,  199 
fermentation  of,  196 
infantile  diarrhea  from,  197 
of  lime,  53 

pasteurization  of,  195 
scarlet  fever  from,  197 
souring  of,  196 
spoiling  of,  196 
tubercle  bacilli  in,  198 
typhoid  fever  and  bacilli  in 

relation  to,  198 
Morax-Axenfeld  bacillus,  135 
Morphology,  224 
of  bacteria,  20 
of  protozoa,  30 
variations  of,  24 


INDEX 


233 


Mosquitoes,    anopheles,    210 
culex,  207,  210 
in  transmission  of  diseases, 
63,  206,  209,  210,  214, 
217 
Moulds,  21,  180,  183 

diseases  due  to,  186,  187 
general  description  of,  183 

to  185 

pathogenic  powers  of,  185 
Mucosus  capsulatus  group,  171 
general      descrip- 
tion of,  171 
pathogenic  power 

of,  174 
poisons,  172 
resistance    of,    to 
heat  and  chem- 
icals, 172 
transmission      of, 

172 

vaccines,  174 
Mumps,  219 
Mycelium,  183 


N 

NOMA,  220 
Nucleus,  24,  30,  224 
Nutrition  of  bacteria,   31, 
of  protozoa,  31 


OIDIUM  albicans,  186 
Ophthalmia  neonatorum,  87 
Opsonic  index,  82 
Opsonins,  69,  224 
Optimum,  224 
Organic,  225 


PARACOLON  bacilli,  169 
Paratyphoid  bacilli,  118 
Parasites,  20,  225 

facultative,  21 

obligate,  21 
Pasteur  treatment  of  rabies,  216 


Pasteurization,  56, 195, 199 
Pathogenic,  225 
Pathology,  225 
Pellagra,  220 
Penicillium  glaucum,  185 
Phagocytes,  69,  225 
Phagocytosis,  69,  225 
Phenol,  52 
Phlegmon,  79 
Pink  eye,  135 
Pityriasis  versicolor,  187 
Plague,  122 

antiserum,  124 
bacillus,  123 

antisera,  125 

general  description  of, 

124 
pathogenic    power  of, 

122,  124 
poisons,  123 
relation  of,  to  plague, 

122 
resistance  of,  to  heat 

and  chemicals,  124 
vaccines,  125 
bacteriological  diagnosis  of, 

124 
disinfection  during  attack, 

123 

immunity  against,  125 
immunization  against,  124 
rat  fleas  in  transmission  of, 

122 

rats  in  transmission  of,  122 
transmission  of,  122 
vaccines  in,  125 
Plane,   225 
Plasma,  225 
Plasmodium,  200 
falciparum,  209 
general  description  of,  213 
life  in  mosquitoes,  211 
malaria?,  209 
pathogenic  powers  of,  211, 

212,  214 
vivax,  209 
Pneumococcus,  90,  94 

in     diseases     other     than 

pneumonia,  91,  95 
general  description  of,  95 
pathogenic  powers  of,  97 
poisons,  97 


234 


INDEX 


Pneumococcus,    relation  of,  to 
pneumonia,  95 

resistance  of,  to  heat  and 

chemicals,  97 
Pneumonia,  94,  172 

bacteriological  diagnosis  of, 
95 

disinfection  during,  95 
Poliomyelitis,  218 

virus  of,  219 
Proliferate,  225 
Protoplasm,  224,  225 
Protozoa,  17,  30,  200 

biological  classification  of, 
21,  200,  225 

centresome  of,  30 

chemistry  of,  32 

cilia  of,  30 

cytoplasm  of,  30 

examination  for,  42 

flagella  of,  30 

morphology  of,  30 

motility  of,  30 

nucleus  of,  30 

nutrition  of,  31 

pseudopods  of,  30 

reproduction  of,  31 

requirements,  32 

temperature  for,  32 

wall,  30 

Protozoology,  17 
Pseudodiphtheria     bacilli,    80, 

104 

Pseudopods,  30,  225 
Ptomain  poisoning,  63 
Pus,  80 

bacillus  of  green,  177 

collection  of,  71 
Putrefaction,  34,  225 
Pyemia,  79,  160 
Pyocyaneus  bacillus,  80,  177 
Pyogenes,  225 


RABIES,  216.  See  Hydrophobia. 

Rain,  bacteria  in,  191 

Ray  fungus,  161.     See  Strepto- 

thrix  actinomyces. 
Relapsing  fever,  205 
Reproduction,  26  to  31 


Rheumatism,    acute   articular, 

219 
Streptococcus 

rheumaticus  in, 

219 

Rhizopoda,  200 
Ringworm,  186 
Room  disinfection,  51,  55 
Russell,  Major,  U.  S.  A.,  anti- 
typhoid vaccination,   117 


S 


Saprophytes,  20,  226 
in  intestine,  35 

Sarcinae,  26 

Sarcodina,  21,  200,  201 

Scarlet  fever,  218 

from  milk,  197 

Schizomycetes,  21 

Septicemia,  60,  79 

Serum,  226 

Sexual,  226 

Silver  nitrate,  49 

Skin  sterilization,  54 

Sleeping    sickness,     204.      See 
Try  panosomiasis . 

Smallpox,  66,  215 

Smegma  bacillus,  155 

Soap,  as  disinfectant,  53 

Sodium  carbonate,  50 
hydroxide,  50 

Soil,  190 

actinomycosis  from,  190 
anthrax  bacillus  in,  190 
bacteria  in,  190 
cholera  bacillus  in,  190 
tetanus  bacillus  in,  191 
tubercle  bacillus  in,  191 
typhoid  bacillus  in,  190 

Soor,  186.    See  Thrush. 

Species,  186 

Spirilla,  21,  24 

Spirillum  cholerae  asiaticse,  125. 
See  Cholera  spirillum. 

Spirochseta,  226 

Obermeieri,  206 
pallida,  147.     See  Trepon- 
ema  pallidum . 

Spontaneous  generation,  19 

Spores,  29,  46,  47,  49,  51 


INDEX 


235 


Sporozoa,  21,  200,  208 
Sputum,  collection  of,  72 

sterilization  of,  54,  143,  146 
tuberculous,  collection  and 
sterilization  of,  55,  143 
Staining,  38,  41 
Staphylococci,  26,  80,  226 
Staphylococcus         epidermidis 

albus,  75,  82 
pyogenes  albus,  82 
aureus,  80 

discovery  of,  85 
diseases  produced 

by,  82 

general      descrip- 
tion of,  81 
resistance    of,    to 
heat  and  chemi- 
cals, 81 
Steam  sterilization,  44,  46,  47 

sterilizer,  44,  46,  47 
Stegomyia  calopus,  217 
Sterilization,   42   to   47,   48  to 

57,  226 
of  dejecta,  54 
of  fabrics,  54 
of  glassware,  42 
hot  air,  47 
incomplete,  48 
of  sputum,  54,  55,  143,  146 
of  utensils,  54 
of  water-closets,  55 
Strain,  226 
Streptococci,    26,    61,    80,    90, 

196,  226 

Streptococcus  pyogenes,  83 
discovery  of,  85 
diseases  due  to,  84,  85 
general  description  of, 

84 

rheumaticus,  219 
Streptothrix  actinomyces,  161. 

See  Actinomycosis. 
general  description  of, 

162 
pathogenic  powers  of, 

161,  163 
poisons,  161 
relation  to  actinomy- 

cosis,  161 

resistance  of,  to  heat 
and  chemicals,  163 


Sulphur  dioxide,  50,  51 

Sunlight,  57 

Syphilis,  147  to  151 
antibodies  in,  149 
diagnosis  of,  149,  151 
forms  of,  148 
skin  reaction  in,  151 
transmission  of,  147 
Wassermann  blood  reaction 
in,  149 


TECHNIQUE,  37 
Temperature  optimum,  45 
Tetanus,  105 

antitoxin,   108 

administration  of,  108 
unit  of,  108 
bacillus,  65,  105 
antitoxin,  108 
effect  of  anaerobic  life, 

106 
general  description  of, 

106 
pathogenic  powers  of, 

105 
relation  of,  to  tetanus, 

105 

resistance  of,  to  heat, 
and  chemicals,   107 
in  soil,  191 
spores  of,  106 
toxins  of,  61,  108 
bacteriological  diagnosis  of, 

106 
disinfection  during  attack, 

106 

Thallophyta,  21 
Thermometer  scales,  47 
Thrush,  186 
Tinea      circinata,       186.     See 

Ringworm. 

sycosis,     186.     See    Ring- 
worm. 

tonsurans,    186    See  Ring- 
worm. 
Toxins,  bacterial,  60,  61,  67,  68, 

226 

extracellular,  61 
intracellular,  61,  67 


236 


INDEX 


Trachoma,  220 
Transmission  of  bacteria,  62 

of  disease,  62 
Treponema  pallidum,  147 

general  description  of, 

149 
pathogenic  powers  of, 

148,  150 
poisons,  148 
relation  of,  to  syphilis, 

147 

resistance  of,  to  heat 
and  chemicals,    149 
transmission  of,  147 
Trichomonas,  208 
intestinalis,  208 
pulmonalis,  208 
vaginalis,  208 
Trichophyton,   184,   186 
Tricresol,  52 
Trypanosoma,  200,  204 

general  description  of, 

206 
pathogenic  powers  of, 

205 
Trypanosomiasis,  204 

transmission  of,  205 
Tsetse  fly,  205 
Tubercle  bacillus,  62,  138 
in  air,  189 
forms  of,  146 
general  description  of, 

145 

in  milk,  142,  198 
pathogenic  powers  of, 

138,  146 

poisons,  141,  146 
relation  of,  to  tuber- 
culosis, 138,  141 
resistance  of,  to  heat 
and  chemicals,    145 
in  soil,  191 
transmission  of,    141 
vaccines,  146 
Tubercles,  139 
Tuberculin,  144,  146,  199 
Tuberculosis,  138  to  147 
agglutinins  in,  144 
antibodies  in  blood  in,  141 
bacteriological  diagnosis  of, 

143 
from  cows,  142,  198 


Tuberculosis,  disinfection   dur- 
ing attack,  143 
forms  of,  139 
from  milk,  198 
skin  test  in,  144 
sputum  in,  disinfection  of, 

143,  146 

transmission  of,  141 
tuberculin  reaction  in,  144, 

199 

treatment,    146 
vaccines,  146 
Tumefaction,  226 
Typhocolon    group    of    bacilli, 

164  to  171 
discovery  of,  171 
Typhoid  bacillus,  61,  80,  109 
agglutinins,  113 
carriers,  112 
general  description  of, 

115 

in  milk,  198 
pathogenic        powers, 

109,  116 
poisons,  112 
relation     to     typhoid 

fever,  109 

resistance  to  heat  and 
chemicals,  115,  116, 
in  soil,  190 
vaccines,  117 
in  water,  110,  193 
fever,  67,  109 

antibodies  after  attack , 

113 

bacteriological  .    diag- 
nosis of,  114 
bacteriolysins  in,    113 
carriers,  112 
disinfection  during  at- 
tack, 112 

immunity   after,   113 
immunization  against, 

116 

Russell's  vaccination 
against,  result  of, 
117 

transmission  of ,  110 
by  flies,  111 
by  ice,   110 
by  milk,  111,  19S 
by  oystors,   111 


INDEX 


237 


Typhoid      fever,     transmission 
of,  by  personal 
contact,  111 
by  sewage,  110 
by       vegetables, 

111,190 

by  water,  110,  193 
Widal  reaction  in,  113 
Typhus  fever,  218 


URINE,  collection  of,  73 
sterilization  of,  54 


VACCINES,  83,  146,  226 

Vaccination,  215 

Vaccine  treatment,  66,  82,  83, 

117,  125,  146 

Variola,  215.    See  Smallpox. 
Vegetables,    in    typhoid    fever 

transmission,  111,  190 
Vegetative  bacteria,  30 
Viable,  226 
Vincent's  angina,  133 

bacteriological      diag- 
nosis of,  134 
disinfection        during 

attack,  134 

general  description  of 
microorganisms    of, 
135 
poisons,  134 


Virulence,  41,  60,  226 
Virus,  41,  226 
Vulvovaginitis,  87 


W 

WATER,  bacteria  in,  191 
-borne  diseases,  192 
cholera  spirilla  in,  192 
colon  bacilli  in,  193 
diseases  transmitted  by,  62, 

192 

dysentery  bacillus  in,   193 
examination  of,  193 
purification  of,  191,  192 
typhoid  bacilli  in,  110,  192, 

193 

fever  from,  110 
Whooping  cough,  136 

Bordet-Gengou    bacil- 
lus in,  136 
general  description  of, 

137 
Widal  reaction,  69,  113 

collection  of  blood  for, 
74 


YEASTS,  21,  180 

diseases  due  to,  181 
general  description  of,  180 
pathogenic  powers  of,  181, 

182 
relation  to  blastomycosis, 

181 
Yellow  fever,  217 

mosquitoes  in,  217 


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